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J Kan-Mitchell

Publications and source records attributed to J Kan-Mitchell.

36 records · Page 2Linked to original sources
PubMed1990

Active-specific immunotherapy for melanoma.

Twenty-five patients with metastatic melanoma were treated with a therapeutic vaccine ("theraccine") consisting of allogeneic melanoma lysates and a novel adjuvant, DETOX (Ribi ImmunoChem Research, Inc, Hamilton, MT). Each patient received 200 antigenic units (20 x 10(6) tumor cell equivalents) subcutaneously on weeks 1, 2, 3, 4, and 6. Clinical responses included one complete remission, three partial remissions, and a long-term (17-month) stability. Two other patients had mixed responses, with partial remissions of numerous subcutaneous nodules. Sites of responsive disease included primarily the skin, but ileal, breast, and a liver metastasis also responded. Removal of residual lesions in patients with partial remissions, whose other lesions had disappeared during treatment, led to long disease-free survivals. The median duration of remission was 17 months, with four of the five responders alive for at least 24 months after treatment. An increase in precursors of cytolytic T cells (CTLs) correlated with clinical outcome, when complete, partial, and mixed responses and long-term stability were considered. The CTLs recognized melanoma-associated antigens on many cell lines, but not other types of tumor or normal lymphocytes. Skin-test reactivity to melanoma antigens and serum antibodies against the melanoma cells was unrelated to clinical response. Toxicity was minimal, restricted largely to minor soreness at the site of injection. Only five patients, four of whom were treated with repeated courses, developed severe granulomas. These results confirm that active-specific immunization with allogeneic lysates of melanoma administered with the adjuvant DETOX can induce immunity to melanoma, and can induce regressions of disease in a proportion of patients with metastatic disease with little toxicity.

Adjuvants, Immunologic↗
PubMed1990

S100 immunophenotypes of uveal melanomas.

To determine whether ocular melanomas are immunophenotypically identical to cutaneous melanomas, 34 primary and metastatic choroidal melanomas representing all major histotypes defined by the Callender's classification, plus one melanoma of the iris and one conjunctival melanoma, were subjected to a panel of immunostains designed to distinguish anaplastic biopsies of cutaneous melanomas from carcinomas and lymphomas. All ocular melanomas were found to express the intermediate filament vimentin but not keratin, and all but 2 were melanotic by immunostaining. Thirty-three of 34 (97%) choroidal melanomas were strongly stained with a rabbit polyclonal antibody (P-S100) developed against the S100 protein family. In contrast, none of 14 spindle cell type primary lesions was stained with a monoclonal antibody (MAB-079) specific for both S100 alpha and S100 beta, the best-characterized S100 polypeptides. Furthermore, only 2 of 5 epithelioid and 3 of 10 mixed-cell-type melanomas were weakly reactive. Overall, 14.7% (5 of 29) were stained. In comparison, MAB079 stained 85% of all cutaneous melanomas. Five metastases of choroidal melanomas (spindle B, epithelioid, and mixed cell types) from different organ sites also were stained by P-S100 but not by MAB079. These findings were corroborated by immunostaining with another monoclonal antibody (MAB4D4) specific for S100 beta. Differential staining by the polyclonal but not the monoclonal antibodies suggests the possible presence of a variant S100 polypeptide(s) in choroidal melanomas. Since S100 alpha, S100 beta, and related proteins appear to be physiologically important, additional studies of these S100 proteins may shed light on the etiology or pathology of choroidal melanomas.

Antibodies, Monoclonal↗
PubMed1989

Tumor-reactive human immunoglobulin G monoclonal antibody from a melanoma patient.

To study tumor-associated antigens that are immunogenic to humans, we have generated human monoclonal antibodies by fusing lymph node lymphocytes of a melanoma patient with a mouse myeloma cell line. We examined in detail the reactivity of one IgG antibody, termed 2-139-1. Immunostaining was performed with purified antibody conjugated to biotin. Binding was visualized by the avidin-biotin-peroxidase complex. With cultured cells, 2-139-1 stained 12 of 12 melanomas and 12 of 16 carcinomas. Reactivity was not detectable in seven neural crest tumors, six sarcomas, and 45 lymphomas and leukemias. This spectrum of reactivity was confirmed with sections of human tissues. The human monoclonal antibody 2-139-1 reacted against melanomas and not banal nevi. While the antibody reacted strongly to adenocarcinomas of the colon, prostate, rectum, and pancreas, it did not stain all the carcinomas tested. Furthermore, reactivity was not seen against sarcomas. Interestingly, 2-139-1 did not bind to the majority of the cells in normal tissues, including fetal tissues. The reactivity of 2-139-1 may be representative of the humoral immune response found in the regional lymph nodes of cancer patients. The distribution of this epitope in various tumors was fairly limited and appeared to be associated with malignant transformation.

Antibodies, Monoclonal↗
PubMed1989

Human monoclonal antibodies reactive with colon carcinoma: identification by a novel screening procedure with xenografts.

To identify tumor-associated antigens immunogenic to man, human monoclonal antibodies (MAbs) were generated by fusing regional lymph node lymphocytes (LNLs) of each of three colon adenocarcinoma patients with the M5 mouse myeloma cell line. Heterohybridomas in 19 wells secreted human immunoglobulin (Ig) for at least 60 days. To identify immunoreactive MAbs, we devised an immunohistochemical assay with xenografts of six colon tumors. Binding was visualized with a biotin-conjugated goat antihuman Ig antibody followed by an avidin-biotin-peroxidase complex. This assay detected binding with a sensitivity of 0.5 microgram/ml human Ig. Reactivity against tumor-associated antigens (TAAs) in frozen sections of the colon xenografts was detected in 14 of the 19 supernates. However, only nine (three IgGs, five IgMs and one IgA) were reactive against formalin-fixed sections, showing that formalin-fixation destroyed some but not all antigenicity. Four MAbs were cloned and tested against the entire panel of 19 xenografts. One IgM MAb reacted only against colon carcinomas, while the other three (one each of IgA, IgG and IgM) had broader reactivities. Three of the four human MAbs did not cross-react with melanomas. In summary, human regional lymph nodes contain a high proportion of B lymphocytes sensitized to the autochthonous tumor. Immunostaining of human colon tumor xenografts can readily identify human MAbs reactive with colon carcinomas.

Animals↗
PubMed1989

Reactivity of a human monoclonal antibody against carcinomas and other lesions of the colon.

To identify tumor-associated antigens that may be immunogenic to man, human monoclonal antibodies (human mAb) were generated by fusing nonsecreting mouse myeloma cells with lymphocytes from regional mesenteric nodes of patients with adenocarcinomas of the colon. One IgG1 human mAb, designated as 14-31-10, was identified by its reactivity against human tumor xenografts. We have studied the reactivity of mAb 14-31-10 with formalin-fixed, paraffin-embedded specimens of human colon. A total of 86 cases were studied, including normal adult and fetal colons, adenocarcinomas of the colon, and a variety of colonic inflammatory diseases and preneoplastic lesions. Intense reactivity was found in 15 of 18 adenocarcinomas of the colon, but not in 10 specimens of normal adult or 4 specimens of fetal colonic mucosa. Interestingly, in four cases of carcinoma, reactivity was also observed in histologically normal mucosa situated 10 cm or more from the primary lesion. On the other hand, no staining was detected in any of the 16 inflammatory lesions. Of the 38 preneoplastic lesions, only 6 showed staining by the mAb: 1 of 5 benign tubular adenomatous polyps, 3 of 9 villous adenomas and tubovillous polyps, 1 of 5 specimens of ulcerative colitis and 1 of 19 specimens of familial polyposis. However, the intensity of staining was only moderate in those cases. Our data, therefore, suggest that the epitope identified by the human mAb 14-31-10 shows preferential expression in preneoplastic and neoplastic lesions of the colon, and in ostensibly normal mucosa at some distance from a primary colonic carcinoma. In all instances, the staining was cytoplasmic, suggesting a cytoplasmic or internal membrane location of the target antigen. This antigen appeared to be distinct from carcinoembryonic antigen, since staining by 14-31-10 was consistently different from that of a mouse monoclonal antibody to carcinoembryonic antigen in serial sections of the same specimens. The restricted reactivity of 14-31-10 suggests its potential application in immunohistochemistry. Moreover, the epitope identified by mAb 14-31-10 may be expressed during the progression of normal mucosa to neoplasia.

Animals↗
PubMed1989

Monoclonal antibody L/1C2 reactive with a human carcinoma associated antigen.

A murine IgG3 monoclonal antibody which defines a human carcinoma associated antigen is described. The antibody, designated L/1C2, was made against a human lung squamous cell carcinoma line designated USCLS-1. It reacts with the surface of 15 of 16 viable human carcinoma cell lines and was detected in 70 of 78 frozen sections of human carcinomas. Melanoma cell lines and frozen sections of melanomas and a lymphoma were unreactive. Normal tissue reactivity included vessels, plus some ducts, glandular structures, and epithelial surfaces. Similar normal tissue reactivity patterns were seen with Rhesus monkey tissue samples. Immunoprecipitation studies indicate that L/1C2 reacts with a glycoprotein doublet which migrates in the range of 110,000 to 140,000 Mr under reducing conditions. Fluorescence analysis suggests this antigen is internalized following reaction with the L/1C2 antibody. Using in vitro human tumor cell growth inhibition assays, it was possible to achieve significant growth inhibition with L/1C2, while another target cell-reactive antibody in the same assay had no inhibitory effect.

Adenocarcinoma↗
PubMed1989

Characterization of uveal melanoma cell lines that grow as xenografts in rabbit eyes.

Two cell lines, OCM-1 and OCM-2, were established from biopsied specimens of choroidal melanomas of spindle B and mixed cell type morphologies. Both cell lines were phenotypically malignant. Karyotypic analyses revealed human chromosomes with a modal number of 95 and 85, respectively. These cell lines have been passaged for over 2 years and are essentially immortal. The cells grew without contact inhibition as monolayers in liquid culture or as clones in soft agar. Electron microscopy revealed melanoma cells containing premelanosomes and cultures free from contamination by fibroblasts. To categorize the morphologies of these cultured cells better by the Callender classification, they were grown as xenografts in the anterior chambers of rabbits immunosuppressed with daily i.m. doses of Cyclosporin A (10 mg/kg). Tumor plaques were detected after 10 days. The eyes were enucleated and fixed in formalin and stained with hematoxylin and eosin for histopathological evaluation. The xenograft from OCM-1 was found to consist predominantly of spindle B-type melanoma cells. In contrast, the xenograft from OCM-2 contained epithelioid, spindle B and clear cell ("balloon") melanoma cells. The ability of these cell lines to grow as xenografts confirmed their neoplastic origin. In fact, the types of the uveal melanoma cells in the xenografts resembled those in the original biopsied tumors. This suggests that the morphology of human uveal melanoma cells is an inherited trait and may be genetically fairly stable.

Animals↗
PubMed1988

Active specific immunotherapy for melanoma: phase I trial of allogeneic lysates and a novel adjuvant.

A Phase I trial of active specific immunotherapy for melanoma was performed to measure the toxicity and immunological effects of the therapy. A mixture of mechanical lysates (homogenates) of two melanoma cell lines was injected together with a novel adjuvant, DETOX, into 22 patients. Several types of cell-mediated and humoral immunity to melanoma-associated antigens were measured serially. In the 17 patients with measurable disease, the sizes of lesions were also noted serially. At least six patients per group were injected s.c. with either 100, 200, or 400 antigenic units (approximately 10, 20, and 40 million tumor cell-equivalents) of the lysates mixed with 0.25 ml of DETOX s.c. on weeks 1, 2, 3, 4, and 6. Three patients at each dose level also received 300 mg/m2 of cyclophosphamide i.v. 4 days before the start of immunization. Evidence for successful immunization was obtained in 13 of the 22 patients. An increase in the frequency of peripheral blood cytolytic lymphocyte precursors reacting against melanoma cells occurred in 12 patients, as measured by a limiting dilution assay involving in vitro re-exposure to irradiated melanoma cells for 9-10 days. Eight of the 12 patients had received cyclophosphamide. By cold-target competition assays, these cytolytic lymphocytes appeared to be atypical T-cells, which recognized melanoma-associated antigens on several allogeneic lines without apparent major histocompatibility complex restriction. An increase in antibody titers against melanoma-associated antigens, measured by enzyme immunoassay, was found in five of 22 patients, and a change in delayed hypersensitivity against the melanoma lysate, in three patients. Responses were found at all three dosage levels of lysate, without an obvious dose optimum. No toxicity except minor local soreness was noted. Therefore, no maximum tolerable dose was defined. Five of 17 patients with measurable lesions had a remission of their melanoma, two complete and three partial, with three additional minor responses. A patient whose complete remission lasted 5.5 months, has no evidence of disease 22+ months after entry onto the study, with the aid of surgical resection of small s.c. recurrences on two separate occasions. Sites of regression included s.c. nodules, lymph nodes, and pulmonary nodules, with no responses in liver, adrenal gland, or bone. The patients who had an increase in cytolytic lymphocyte precursors comprised all eight with a clinical remission (five major, three minor). In contrast, none of the seven patients lacking an increase in cytotoxic lymphocytes had a clinical response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1987

Altered antigenicity of human monoclonal antibodies derived from human-mouse heterohybridomas.

We have generated milligram quantities of human monoclonal antibodies (Hu-MAbs) in the ascites of pristane-primed nude mice injected with human-mouse heterohybridomas. After contaminating mouse immunoglobulins were removed by affinity chromatography, an enzyme immunosorbent assay (EIA) was used to measure the concentrations of human immunoglobulins. Ten different partially purified preparations were tested. The titration curves with all 5 IgG Hu-MAbs were unusual, reaching a plateau at a very low apparent maximum concentration of antibody. In contrast, the EIA yielded more usual titration curves and thus apparently more reliable estimates of the concentrations of 4 IgM and 1 IgA monoclonal antibodies. An analogous EIA for the quantitation of mouse IgG monoclonal antibodies also gave accurate estimates. To understand the nature of the discrepancy with human IgG, 5 Hu-MAbs of the 3 classes (2 IgG, 2 pentameric IgM and 1 IgA) were purified to homogeneity for a more detailed analysis. The inability to quantitate the human IgG monoclonal antibodies by EIA was not due to defective molecules, as shown by SDS polyacrylamide gel electrophoresis. The human IgG monoclonal antibodies were found to consist of intact heavy and light chains, as were the IgM and IgA antibodies. The possibility that the human IgG monoclonal antibodies differed antigenically from polyclonal IgG was explored by comparing the concentrations by EIA with the protein concentrations determined by absorbance at 280 nm. This analysis permitted a comparison of the detectability of antigenic determinants on Hu-MAbs with those on polyclonal Ig with goat antibodies to Ig or Ig subclass. The IgG monoclonal antibodies differed from polyclonal IgG in both their heavy and light chains. Goat antiserum monospecific for the gamma chain in fact underestimated the concentration by as much as one hundred-fold. IgM and IgA monoclonal antibodies were less antigenically distinct from their polyclonal counterparts even though their light chains were also underestimated, because goat monospecific antibodies were more efficient at recognizing their heavy chains. The molecular basis for the observed difference in antigenicity is not yet known. These findings have important implications for the analysis of the binding of IgG Hu-MAbs. A direct binding assay with the label directly conjugated to the Hu-MAb should be used in preference to an indirect assay with a labeled detecting antibody to maximize the sensitivity of the assay. The altered antigenicity of IgG Hu-MAbs may also imply decreased immunogenicity when they are given in vivo as carriers for radionuclides or cytotoxic antitumor materials.

Animals↗
PubMed1986

Human monoclonal antibodies that distinguish cutaneous malignant melanomas from benign nevi in fixed tissue sections.

Human monoclonal antibodies were generated by fusing a nonsecretory variant of murine myeloma cells with lymphocytes obtained from the lymph nodes of patients with metastatic cutaneous malignant melanoma. Two human IgG monoclonal antibodies, designated 2-139-1 and 6-26-3, were extensively studied for their patterns of binding to cells in 64 specimens of formalin-fixed, paraffin-embedded tissue sections. These comprised: 23 cutaneous and 2 ocular melanomas; 4 specimens of lentigo maligna; 27 benign nevi; 2 basal and 2 squamous cell neoplasms of the skin; and 4 specimens of normal skin. A direct avidin-biotin-immunoperoxidase staining method was used. Under these conditions, the antibodies reacted with variable intensity to all 18 primary cutaneous malignant melanomas, 5 metastatic cutaneous melanomas, and both ocular melanomas. Antibody 2-139-1 reacted with 1 of 4 specimens and 6-26-3 with 3 of 4 specimens of lentigo maligna. Two of 5 dysplastic nevi reacted with both antibodies, each with a smaller proportion of cells than with melanomas. There was no reactivity with the 22 other nevi representing a spectrum of histologic types or with normal melanocytes. Basal cell and squamous cell carcinomas of the skin also were not stained. These human monoclonal antibodies appear to be useful in distinguishing malignant melanomas from benign nevi, with the exception of dysplastic nevi, and from basal and squamous cancers of the skin in routinely prepared tissue sections. They may also help to identify the cytoplasmic antigens that are immunogenic in humans.

Antibodies, Monoclonal↗
PubMed1986

Human monoclonal antibodies directed against melanoma tumor-associated antigens.

To analyze the humoral immune response to melanoma, human-mouse hybridomas were generated by the fusions of regional lymph node lymphocytes of patients with the mouse myeloma cell line M5. Six stable hybridomas were cloned from six separate lymphocyte parents obtained from three patients. Ascites were obtained from nude mice after i.p. injection with cultured hybridoma cells. The monoclonal antibodies, four immunoglobulin Gs and two pentameric immunoglobulin Ms, were partially purified to remove mouse immunoglobulin and then conjugated to biotin for immunocytochemical and immunohistochemical studies. With the avidin:biotin:peroxidase complex method to detect and amplify binding by the biotin-conjugated human monoclonal antibodies, we found the six antibodies to be reactive against cytoplasmic determinants in five short-term melanoma cultures and formalin-fixed paraffin-embedded melanoma tumors from four patients. The antigenic target of the antibodies identified was not carcinoembryonic antigen. Two antibodies, 2-139-1 and 6-26-3, were studied in more detail. Each stained 25 of 25 specimens of melanomas. Little or no reactivity was detected against fixed sections of normal skin, which included tissues such as epidermis, dermis, monocytes, lymphocytes, and vascular endothelium. More striking was the absence of binding to melanocytes in the basal layer of the skin or to pigmented nevus cells. Both antibodies showed cross-reactivity against other tumors, in particular colonic and prostatic carcinomas. In the normal colon, reactivity was restricted to the surface of the columnar epithelium; no reactivity was detected against normal prostatic epithelium. Reactivity was also not observed against liver and lung. However, the epithelia of the renal tubules, pancreatic ducts, and salivary ducts were all reactive. These human monoclonal antibodies identify cytoplasmic melanoma-associated tumor antigens that appear different from the membrane antigens defined by serological approaches and by most mouse monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1985

Correlation between cytotoxic and suppressor activities of human pulmonary alveolar macrophages.

We have reported previously that pulmonary alveolar macrophages (PAMs) from individuals with lung cancer and active chronic pulmonary diseases were cytotoxic to tumor cells in vitro, whereas PAMs from normal individuals or patients with acute pulmonary disorders were noncytotoxic. In the present study, we evaluated 20 PAM preparations for both suppressor and cytotoxic functions to determine if PAMs could function as suppressor cells and, if so, whether a correlation between the two functions exists. Cytotoxicity was assessed in a 60-hr cytotoxicity assay against [3H]proline-prelabeled human melanoma target cells. More than 20% cytotoxicity was considered to be significant. Suppressor activity was measured by determining whether admixing PAMs at various ratios with autologous or allogeneic mononuclear cells could suppress concanavalin A-induced blastogenesis by T-lymphocytes. At least 50% suppression was considered to be significant. Of the 20 specimens evaluated, 13 were cytotoxic and 5 of these exhibited suppressor activity. None of the 7 noncytotoxic PAM preparations had suppressor activity. Suppression was nonspecific and not HLA restricted, since autologous and allogeneic mononuclear cells were inhibited to a similar extent. Suppression was probably not due to prostaglandin production by the PAMs since assays were performed under optimal conditions and required extremely high concentrations of prostaglandins. A significant correlation between suppressor and cytotoxic activity was found. Suppression was observed only with PAM specimens that were also highly cytotoxic to tumors, but not all cytotoxic PAM specimens were suppressive. Whether these actions reflect different levels of activation of PAMs or are the properties of different macrophage subsets remains to be clarified.

Concanavalin A↗
PubMed1985

Cytotoxic activity of human pulmonary alveolar macrophages.

The functions of human pulmonary alveolar macrophages (PAMs) have been relatively little studied compared with those of their circulating counterparts, blood monocytes. This study examined the ability of human PAMs to kill primary human tumor cell cultures and control normal fibroblasts in vitro. PAMs were derived by bronchial lavage from patients with lung cancer of various histological types and stages, patients with acute or chronic noncancerous pulmonary disorders, and subjects with a presumed illness who proved to be normal. After extensive washing, the PAMs were cocultured with [3H]proline-labeled tumor cells, principally lung cancers and melanomas, at various effector:target ratios for 60 hr. Cytotoxicity was measured by comparing radioactivity associated with the remaining adherent tumor cells cultured in the presence or absence of PAMs. Twenty-eight of 42 preparations of PAMs from 42 individuals were cytotoxic to one or more short-term primary tumor cultures. All 28 specimens from patients with lung cancer or chronic pulmonary disease were cytotoxic; all of the 14 PAM preparations lacking cytotoxicity were from individuals with acute pulmonary disorders or who were proved free of pulmonary disease. PAMs were cytotoxic even at effector:target ratios of 2.5:1 or 1.25:1. Fibroblasts were unaffected at any ratio. Sarcoidosis patients in remission had noncytotoxic PAMs, whereas the disease in relapse was characterized by cytotoxic PAMs. Serial study of 2 patients confirmed a loss of reactivity during remission. Smoking did not correlate with the presence or absence of spontaneous cytotoxicity and did not influence the degree of cytotoxicity in "reactors." Partially purified alpha-interferon enhanced the killing of cytotoxic PAMs in 10 of 21 instances but did not induce cytotoxicity in 9 tests on nonreactive PAMs. We conclude that human PAMs from patients with lung cancer or chronic pulmonary diseases, including active sarcoidosis, were cytotoxic to several recently explanted tumor cell cultures. PAMs from acute pulmonary dysfunctions and those from patients with inactive sarcoidosis were not spontaneously cytotoxic.

Adenocarcinoma↗
PubMed1983

Immunological effects of recombinant interferon-alpha 2 in cancer patients.

Fifteen patients with various types of cancer, resistant to conventional therapy, were entered into a phase I trial of pure interferon-alpha 2 (IFN-alpha 2) produced by recombinant DNA technology. Groups of patients received either 3, 10, 30, or 50 x 10(6) units (U) of IFN-alpha 2 subcutaneously daily for 4 weeks and were closely followed for possible toxicity. At the higher doses, toxicity was encountered, which led to reduction in the frequency of administration. For immunological testing, peripheral blood mononuclear cells were obtained before treatment on day 1, on day 2, and during the 2nd, 3rd, and 7th weeks of the study. The cells were tested for natural killer (NK) activity, antibody-dependent cellular cytotoxicity (ADCC), monocyte-mediated antibody-dependent cellular cytotoxicity (MMADCC), and spontaneous monocyte-mediated cytotoxicity (SMC). ADCC was augmented at all doses in 9 of 15 patients, 6 of whom exhibited elevated levels by day 2. In direct contrast, MMADCC was decreased in 12 of 14 patients 7-20 days after beginning treatment. SMC was increased on day 2 in 1 of 2 patients given 3 x 10(6) U and in 3 of 4 patients given 10 x 10(6) U. SMC in the other patients given these doses was unchanged on day 2, with no decreases noted. In contrast, SMC was decreased in 2 of 4 patients given 30 x 10(6) U. SMC in the other patients given these doses was unchanged on day 2, with no decreases noted. In contrast, SMC was decreased in 2 of 4 patients given 30 x 10(6) U and in 2 of 3 patients given 50 x 10(6) U. NK cell activity was increased in 2 of 3 patients given 3 x 10(6) U, but was either unchanged or decreased in patients given higher doses. The only exception was an increase found in a patient given 50 x 10(6) U, whose renal cell carcinoma responded significantly to treatment. Data on NK and SMC from a phase II study of breast cancer treated daily with 3 x 10(6) U IFN-alpha 2 support our phase I observations. NK-cell activity was increased on day 2 in 3 of 8 patients, and SMC increased in 2 of 8 patients. As in the phase I study, no decreases in these functions occurred. In summary, for those responses that were dose dependent, such as NK and SMC, lower doses of recombinant IFN-alpha 2 (3 x 10(6) and possibly 10 x 10(6) U) may be more effective in increasing these antitumor activities than are higher doses.

Adult↗
PubMed1980

Structural evidence for distinct IgG subclass-specific Fc receptors on mouse peritoneal macrophages.

Membrane proteins which selectively bind to the Fc portion of IgG were identified in the Nonidet P-40 extracts of radiolabeled thioglycollate- elicited mouse peritoneal macrophages. Affinity columns of various IgG preparations coupled to Sepharose 4B were used to absorb the Fc-binding proteins. Analysis of the acetic acid or sodium dodecyl sulfate (SDS) eluates from aggregated human IgG or antigen-complexed rabbit IgG columns revealed two Fc(gamma)/-specific proteins with apparent 67,000 and 52,000 mol wt. These proteins were not detected in acid or SDS eluates from F(ab')(2) columns or in eluates from IgG column, over which were passed lysates of Fc receptor-negative cells. With the use of affinity columns that contained aggregated mouse myeloma proteins of different IgG subclasses, we found that the 67,000-dahon protein selectively binds to IgG2a, whereas the 52,000-dalton protein binds to IgG1 and IgG2b. Neither protein was found in SDS eluates from IgG3 columns. Trypsin treatment of the macrophages before detergent lysis removed the 67,000-dalton protein, although it leaves intact the 52,000-dalton protein. These results provide structural confirmation for the existence of separate Fc receptors on mouse macrophages and indicate that the two Fc-binding proteins identified in this study represent all or part of the trypsin- sensitive Fc receptor which binds IgG2a and the trypsin-resistant Fc receptor which binds IgG2b and IgG1.

Animals↗
PubMed1980

Comparative analysis of the immunosuppressive properties of two antiviral, iodinated thymidine analogs, 5-iodo-2'-deoxyuridine and 5-iodo-5'-amino-2',5'-dideoxyuridine.

5-Iodo-5'-amino-2',5'-dideoxyuridine (AldUrd), given as five single i.p. injections on Days 0 to 4 after antigenic challenge with sheep erythrocytes, had no demonstrable effect on serum hemagglutinin titers in doses as high as 2000 mg/kg/day. This was the maximum feasible single dose, but no 10% lethal dose was determinable. Similarly, 5-iodo-2'-deoxyuridine (IdUrd), 50 mg/kg/day (10% lethal dose), on Days 0 to 4 did not significantly affect this humoral response. However, with a more sensitive assay, immunocytoadherence, reductions in the number of hemagglutinin-forming cells in the spleen were found at several levels of AldUrd and IdUrd, but the same level of inhibition was attained by a course of AldUrd, 2000 mg/kg, or IdUrd, 50 mg/kg. Spleen cell-mediated immunity against lethally irradiated L1210 was measured by 4-hr 51Cr release and 48-hr growth inhibition assays. Both drugs showed dose-related immunosuppression. With AldUrd, 2000 mg/kg/day, and IdUrd, 100 mg/kg/day, on Days 0 to 4, cytotoxicity was inhibited by 35 to 68% and 73 to 90%, respectively. In comparison, a similar course of 1-beta-D arabinofuranosylcytosine, 40 mg/kg/day, completely abrogated both humoral and cell-mediated immunity. When AldUrd and IdUrd were administered on Days -5 to -1, little effect on either type of immunity was found, while pretreatment with the alkylating agent, cyclophosphamide, abolished all T-cell-mediated killing as measured on Day 7. Thus, AldUrd appears to be a very mild and IdUrd a moderate to strong cell cycle-dependent immunosuppressive.

Animals↗