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PubMed1984

Phagocytic cell function in response to immunosuppressive therapy.

The increased incidence of pulmonary infection in human renal allograft recipients is presumably related to antirejection immunosuppressive therapy. To assess immunosuppressive-related disturbances of the immune responses of the lung, we evaluated the functional abilities of the pulmonary alveolar macrophage (PAM) and polymorphonuclear leukocyte (PMN) of rats in chemotaxis, phagocytosis, and superoxide-release assays following 30 days of intraperitoneal administration of cyclosporine, azathioprine, and/or prednisolone sodium succinate. None of these drugs affected superoxide release by stimulated PAMs or PMNs. Except for a transient inhibition by azathioprine, the drugs had no effect on phagocytosis of Staphylococcus aureus by either cell type. On the other hand, cyclosporine inhibited formyl-methionyl-leucyl-phenylalanine (FMLP)-directed chemotaxis by PAMs, and both FMLP and C5a stimulated chemotaxis by PMNs. Azathioprine had more dramatic effects on PAMs than on PMNs and prednisolone at 2 mg/kg inhibited PAMs. The results indicated that, with the exception of chemotaxis, the immunosuppressive agents largely spare nonspecific elements of host defense.

Animals↗

PubMed1996

New immobilization chemistry for probe affinity mass spectrometry.

Probe affinity mass spectrometry (PAMS) is a technique that combines affinity separations directly with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). In this approach, a binding molecule, such as an antibody, lectin or receptor, is covalently attached to the surface of a MALDI probe. This permits the analyte of interest to be selectively captured and concentrated on the probe surface prior to MALDI-MS analysis. A major limitation of our initial PAMS immobilization chemistry was that it produced only a relatively small number of binding sites on the probe, as it was based on forming a single monolayer of the binding molecule. Because of this limitation, we have investigated new immobilization chemistries for PAMS that are not confined by monolayer formation and thus allow a larger number of analyte molecules to be captured by the probe. We have developed a new PAMS chemistry that first attaches very high molecular weight (approximately 500,000) dextrans to the MALDI probe, followed by immobilization of the binding molecules to the probe-bound dextrans. Because the size of each dextran molecule is significantly larger than the binding molecule, multiple binding molecules can be linked to the same dextran chain. We have demonstrated that these surfaces possess approximately 500 times more analyte binding sites than probes prepared with our original PAMS chemistry. This chemistry is applicable to any binding molecule that contains a primary amine and is suitable, therefore, for a wide range of applications.

Chromatography, Affinity↗

PubMed1981

A randomized comparative trial of chemotherapy and irradiation therapy for stage II breast cancer.

One hundred fifty-eight evaluable patients with Stage II carcinoma of the breast with positive lymph nodes were treated either with adjuvant chemotherapy or irradiation therapy followed by chemotherapy. Patients were randomized to test the effectiveness of L-phenylalanine mustard (L-PAM) with and without postoperative irradiation therapy (R.T.) against cyclophosphamide, 5-fluorouracil, and methotrexate (CMF) with and without postoperative irradiation therapy in decreasing the frequency of recurrence. No significant difference was observed between L-PAM as compared with R.T. plus L-PAM (P = 0.85). The difference between CMF and R.T. plus CMF was significant in support of CMF alone (P = 0.04). The frequency of recurrence between R.T. plus L-PAM and R.T. plus CMF showed no difference. A comparison of the chemotherapy only regimens showed an advantage of CMF over L-PAM (P = 0.05). Both the delay in starting chemotherapy and the significant decrease in percent optimal drug dosage during the first six cycles of therapy are factors that may influence the high frequency of relapse observed in the R.T. plus chemotherapy groups. Of the four treatments, CMF has the lowest frequency of recurrence.

Adult↗

PubMed1983

The use of intravenous phenylalanine mustard followed by supervoltage irradiation in the treatment of carcinoma of the ovary.

Between 1970 and 1980, 50 patients with carcinoma of the ovary were treated sequentially with six courses of IV phenylalanine mustard (L-PAM), second look surgery, and radiotherapy using the strip technique. Seven patients had advanced Stage I disease and six patients had Stage II disease; all of these patients are alive and well with no evidence of disease (NED) with a mean survival of five years. Thirty-seven patients had Stage III disease: ten of these patients did not respond to L-PAM (26%); 17 patients had a partial response (48%), and four of these (22%) are alive with NED and a mean survival of five years; ten patients (26%) had a complete response to L-PAM and all are alive and well with a mean survival of five years. The presence of a minimal tumor burden after the initial surgery, a mixed histology, a low-grade differentiation, suppression of leukocyte count to below 2000/mm3 after the first course of chemotherapy, and a complete response to L-PAM, were all factors that contributed to the probability of a long-term survival. Tumors responding to L-PAM and then recurring also responded to a combination of cisplatin and adriamycin, and hexamethylmelamine.

Adult↗

PubMed1984

Comparison of melphalan with cyclophosphamide, methotrexate, and 5-fluorouracil in patients with ovarian cancer.

Melphalan (L-PAM) was compared to (C) cyclophosphamide, (M) methotrexate, and (F) 5-fluorouracil (CMF) in 413 patients with advanced ovarian carcinoma. L-PAM was given 3.5 mg/m2 twice daily for 5 days every 5 weeks. CMF doses were: C, 400 mg/m2; M, 15 mg/m2; and F, 400 mg/m2 IV on days 1 and 8 every 28 days. Three hundred seventy-five patients have been analyzed (L-PAM, 190; CMF, 185). One hundred fifty-three patients (41%) had measurable disease, 109 (29%) had evaluable disease, and 113 (30%) had nonmeasurable, nonevaluable disease. Response rates for patients with measurable and evaluable disease combined were similar: L-PAM, 32/130 (24%) (15% complete response); CMF, 47/132 (35%) (18% complete response). Patients with Stage IV measurable disease had a greater response rate to CMF, 22/52 (42%) versus L-PAM, 6/39 (15%). Survival and time to treatment failure were similar for both treatment regimens. Survival was improved in responders. Medians are: complete response, 28.1 months; partial response, 12.3 months; and no response, 6.7 months. Disease stage, performance status and age were identified as important prognostic variables for both survival and time to treatment failure.

Adenocarcinoma↗

PubMed1981

Periarterial macrophage sheaths (ellipsoids) in cat spleen--an electron microscope study.

Periarterial macrophage sheaths (PAMS), a term we introduce to replace "ellipsoids," surround arterial capillaries in the red pulp of the spleen and are major sites for clearance of blood-borne particles. PAMS and their arterial capillaries in cat spleens in various states of congestion and contraction were studied by transmission electron microscopy. Thorotrast, a colloidal suspension of thorium dioxide, was injected to label macrophages. A PAMS consisted of a fine meshwork of reticular cells and reticular fibers which held macrophages and formed a cylindrical sheath around an arterial capillary lying in its longitudinal axis. Some PAMS were spongy due to loosening of cell associations by plasma infiltration; others were tightly compressed. Blood cells were both free in the interstices of the PAMS and attached to macrophages. Reticular cells formed a closely applied but incomplete layer adventitial to the arterial capillary and extended branches which contributed to the meshwork. Small villous processes on the major branches of reticular cells approached each other, sometimes forming intercellular junctions, and fit into complementary indentations in the surfaces of macrophages and endothelial cells. Thin filaments within reticular cells filled the villous processes and formed a border beneath the plasmalemma; intermediate filaments ran through the centers of the branches. Reticular fibers lay between reticular cells. Basement membrane fabricated of the same material as reticular fibers lay between the endothelium and reticular cells. Macrophages contained Thorotrast and abundant debris of phagocytized cells and were joined by extensive interdigitation of micropseudopodia. Endothelial cells were long rods which lay parallel and were joined along their bases by interdigitating lateral processes. Intercellular junctions were present at some points, but at others lateral processes were everted to form open interendothelial slits through which blood cells could pass. Endothelial cells possessed great numbers of randomly oriented intermediate filaments and small patches of thin filaments scattered along the basal plasmalemma and in lateral processes. Thin filaments may function to attach cells to one another and to the basement membrane and may assist in closing interendothelial slits. We believe that the endothelium responds to changes in arterial blood pressure and blood flow. It stretches to allow dilatation and recoils, probably due to the intermediate filaments, squeezing blood cells through interendothelial slits.

Animals↗

PubMed1981

Electron microscopy of the red pulp of the dog spleen including vascular arrangements, periarterial macrophage sheaths (ellipsoids), and the contractile, innervated reticular meshwork.

The vascular and stromal arrangements of the red pulp in congested and contracted dog spleens were studied by transmission electron microscopy. Each dog had been injected intravenously with Thorotrast to label actively endocytizing cells. Only macrophages ingested Thorotrast. The proximal portion of each arterial capillary was surrounded by a "periarterial macrophage sheath" (PAMS), a term we introduce to replace the term "ellipsoid". PAMS were composed of a fine meshwork of reticular cells and reticular fibers which held tightly-packed macrophages and interspersed blood cells. These macrophages, as well as those in the reticular meshwork of red pulp, contained Thorotrast, cell debris, and deposits of hemosiderin. The arterial capillary at the center of each PAMS was formed by parallel, rod-shaped endothelial cells and discontinuous layers of basement membrane and reticular-cell cytoplasm. PAMS were tapered at their distal ends; the terminal portion of the arterial capillary continued beyond the PAMS to end in the reticular meshwork of red pulp. Endothelial cells in the terminal arterial capillaries were separated by gaps through which blood cells passed into the spaces of the reticular meshwork of red pulp. The reticular meshwork was formed by reticular cells which appeared to be specialized for contraction. These cells were filled with thin filaments and possessed plasmalemmal dense bodies as found in smooth muscle cells. Furthermore, the reticular meshwork was innervated by unmyelinated adrenergic axons which probably were derived from nerves that followed arterioles. Axons were enclosed in surface invaginations of cells which were similar to reticular cells in shape and cytologic detail and which we called "axon-bearing reticular cells". Axon-bearing reticular cells were inserted between the branches of the reticular cells that formed the meshwork. Venous sinuses formed an anastomosing system of vessels draining into pulp veins which then joined trabecular veins. Sinuses were formed by parallel, rod-shaped endothelial cells encircled by strands of basement membrane and reticular-cell branches. Endothelial cells lay closely side by side except where interendothelial slits were opened by blood cells passing into the lumen or by pseudopodia of macrophages which lay outside the sinus. Cell traffic across the sinus wall was greatest in areas where blood cells were mixed with plasma. Congested spleens stored concentrated red cells in both sinuses and the reticular meshwork; contracted spleens were emptied of blood. The reticular meshwork may contract to assist trabecular and capsular smooth muscle in expelling stored red cells and effecting hemoconcentration.

Animals↗

PubMed1982

Dynamic aspects of the supramolecular organization of intermediate filament networks in cultured epidermal cells.

We have shown, by indirect immunofluorescence microscopy using an antiserum against the mouse keratin subunit K2 and by electron microscopy, that transformed (PAM) and primary (PME) mouse epidermal cells possess extensive networks of IF bundles. Following trypsinization and replating of PAM cells, IF bundles are seen to move as a continuous network from a perinuclear zone into the peripheral cytoplasmic regions. In PAM cells lysed in high-ionic-strength solutions containing Triton X-100 and DNAase-1, IF bundles appear to be closely associated with nuclear envelope remnants and, in some cases, appear to be attached to nuclear pore complexes. PME cells cultivated in low Ca2+-containing medium possess perinuclear birefringent arrays of IF bundles. Within 2 hours of switching the cells to normal Ca2+ levels, the PME IF bundle network moves towards and establishes contact with the cell surface as desmosomes form. Live cells observed by phase contrast and fixed cells observed by immunofluorescence microscopy demonstrate that desmosomes can be distinguished as dark bands separating neighboring cells. There is little difference between the major proteins seen in SDS-polyacrylamide gel profiles of isolated IF bundle networks from PME cells before and after the Ca2+ switch. Therefore, a reorganization of relatively insoluble membrane-associated protein following the Ca2+ switch may be involved in desmosome formation. The isolated IF networks from PAM cells differ in protein composition compared to the PME IF networks. This may be related to the greatly reduced number of desmosomes in PAM cells. The IF bundle system in epidermal cells appears to be involved in shape formation, shape maintenance, the establishment of desmosomes, nuclear centration, and cell-cell contact.

Animals↗

PubMed2006

Zebrafish protocadherin 10 is involved in paraxial mesoderm development and somitogenesis.

Here, we present the first report of the molecular cloning of zebrafish protocadherin 10 (Pcdh10, OL-protocadherin) and describe its functional analyses in the development of segmental plate. Epitope-tagged Pcdh10 expressed in embryos was localized on cell peripheries of adjacent cells. In situ hybridization showed that pcdh10 was expressed in the paraxial mesoderm (PAM) and developing somites, and in the pineal body, the diencephalon, and the vicinity of otocysts. Expression in PAM increased in the last few presumptive somites, reached the maximum level in the latest segmenting somites, and decreased thereafter during somite maturation. These expression patterns suggested that Pcdh10 is involved in development of PAM and somites. This was confirmed by morpholino knockdown and dominant-negative inhibition of Pcdh10 in embryos, which disturbed movements of PAM cells and somite segmentation. Comparative studies showed that pcdh10 expression lasted up to approximately three times longer in maturing somites than that of paraxial protocadherin (pcdh8). They also indicated that the adaxial cells expressed pcdh8 but not pcdh10. We propose that Pcdh10 is involved in the morphogenic movements of PAM cells and somite segmentation and that differential adhesion of Pcdh8 and Pcdh10 plays a role in the morphogenic machinery of somites and adaxial cells.

Animals↗

PubMed1985

Pregnancy-associated beta 1-macroglobulin: detection on the surface of ovarian cancer cell lines.

Pregnancy-associated beta 1-macroglobulin (beta 1-PAM) is a serum protein which can be detected at elevated levels in the blood of many ovarian cancer patients. The presence of the antigen was investigated on the surface of 4 human ovarian cancer lines and 32 other human and rodent cell types and lines by means of immunofluorescent staining and anti-beta 1-PAM-enzyme conjugate. The antigen was detected only on the ovarian lines but no secretion of beta 1-PAM into the culture supernatants was observed. The ovarian cancer cells appeared to display the beta 1-PAM constantly during culture, and enzymic treatment of the cells indicated that detection of the cell-bound antigen with antiserum could be, at least partially, eliminated with proteases but not glycosidases or neuraminidase. The results serve to confirm the association of beta 1-PAM with ovarian cancer.

Antigens, Surface↗

PubMed1995

Comparison of cell-cycle phase perturbations induced by the DNA-minor-groove alkylator tallimustine and by melphalan in the SW626 cell line.

Tallimustine or N-deformyl-N-[4-N-N,N-bis(2-chloroethylamino)benzoyl], a distamycin-A derivative (FCE 24517), is a novel anti-cancer agent which alkylates N3 adenine in the minor groove of DNA. The cell-cycle phase perturbations induced by the drug were investigated and compared with those caused by melphalan (L-PAM) in SW626 human ovarian-cancer cells. By coupling bromodeoxyuridine (BUdR) immunoreaction with biparametric flow-cytometric (FCM) analysis, we investigated the cell-cycle phase perturbation induced by tallimustine or L-PAM, considering separately the cells which, during the 1-hr treatment, were in the S phase or in G1-G2/M phases of the cell cycle. L-PAM delayed the S-phase progression of cells exposed to the drug when they were in S phase, with a consequent accumulation of cells as soon as they reached the G2 phase. In contrast, the S-phase cells treated with tallimustine were not perturbed during the DNA-synthesis phase progression, and were blocked in G2 only after they had passed through the G1/S transition of a new cell cycle. In cells which were in G1 or G2/M phases during drug treatment, tallimustine and L-PAM caused similar accumulation in G2. The differences in the cell-cycle perturbation caused by tallimustine and L-PAM may well be related to the different DNA damage the 2 drugs produced. These findings emphasize the different properties of DNA-minor-groove alkylating agents and conventional ones.

Alkylating Agents↗

PubMed1988

Responses of rat alveolar macrophages to inhaled brass powder.

The effects of a single acute exposure to inhaled brass dust on rat pulmonary alveolar macrophages (PAM) were determined. Pulmonary alveolar macrophages lavaged from the lungs of these experimental animals showed both morphological and functional abnormalities. Exposure to brass dust caused a rapid, transient inflammatory response, producing an influx of polymorphonuclear leukocytes into the lavage fluid. Binucleation and multinucleation of PAM were sensitive morphological indicators of pulmonary stress that persisted throughout the 14-day course of the experiment. Pulmonary alveolar macrophages from rats exposed to brass dust were phagocytically activated; both the total numbers of test particulates ingested and the phagocytic index were elevated. Chemotaxis, as measured by direct cellular migration in Boyden chambers, was inhibited for 3 days after exposure, but was markedly stimulated from 7 to 14 days. This was interpreted as a possible consequence of a selective release of lymphokines during the course of the inflammatory response. Some of these results, based on in vivo exposure of PAM to inhaled particulates, differ from those derived from in vitro exposure. This points to the fact that it is virtually impossible to duplicate the native chemical microenvironment of PAM in vitro and emphasizes the necessity of bringing about PAM-particle interactions in the intact lung in order to obtain more physiologically relevant data.

Administration, Inhalation↗

PubMed1984

The proliferation kinetics of pulmonary alveolar macrophages.

In this study the proliferation kinetics of pulmonary alveolar macrophages (PAMs) are determined using [3H]thymidine labeling, flow cytofluorimetry, metaphase arrest, and the percentage of labeled mitoses. The demonstration of in situ PAM proliferation is demonstrated beyond doubt. Comparison of the turnover time, calculated from cell kinetic parameters, with the experimentally determined migration times shows that the contribution proliferating PAMs make to their own population size is significant. Indeed, a strong case may be made to show that some 70% of the PAM population is produced by intra-alveolar divisions of "free" PAMs.

Animals↗

PubMed2004

Reversal of the transformed phenotype and inhibition of peptidylglycine alpha-monooxygenase in Ras-transformed cells by 4-phenyl-3-butenoic acid.

Recent studies have shown that the proliferation of some tumor cells is dependent on autocrine growth loops that require amidated autocrine growth factors. Peptidylglycine alpha-monooxygenase (PAM) is required for amidation of these growth factors and, therefore, this enzyme is an attractive target for anti-tumor compounds. 4-Phenyl-3-butenoic acid (PBA) is an irreversible turnover-dependent inhibitor of PAM in vitro and has been shown to decrease lung cancer cell proliferation by inhibiting the synthesis of amidated growth factors. We show here that PBA (0.1 mg/mL) inhibits the growth of Ras-transformed epithelial cells (WB-Ras) but has little effect on the proliferation of normal epithelial cells (WB-Neo). The methyl ester derivative of PBA (PBA-Me) at 10-fold lower concentration also exhibits a selective inhibition of Ras-transformed cell growth compared to normal epithelial cell growth. In addition, PBA produces a significant upregulation of gap junctional communication between WB-Ras cells following 2-5 day treatments, with a corresponding increase in the degree of connexin 43 phosphorylation and an increase in the number of connexin 43-containing plasma membrane gap junction plaques. Western blot analyses indicate no effect of PBA on the proportion of p21 Ras in the membrane versus cytosolic fractions or on p44/42 MAP kinase phosphorylation. Furthermore, the cell morphology of PBA-treated WB-Ras cells is altered, so as to more closely resemble that of non-transformed WB-Neo cells. PAM activity was assayed in both WB-Ras and WB-Neo cells, and we demonstrate that PBA at long treatment times (4 days) inhibits PAM activity in both cell types at concentrations that produce selective growth inhibition of WB-Ras cells. Shorter PBA treatment times (24 h), however, inhibit PAM activity in WB-Ras but not WB-Neo cells, an effect that was mimicked by PBA-Me. Taken together, these results clearly demonstrate that PBA returns Ras-transformed cells to a more normal phenotype, a finding consistent with the known increased dominance of the Ras signaling pathway in transformed epithelial cells.

Cell Line, Transformed↗

PubMed1981

Investigation on cyclophosphamide treatment during the preimplantation period. II. In vitro studies on the effects of cyclophosphamide and its metabolites 4-OH-cyclophosphamide, phosphoramide mustard, and acrolein on blastulation of four-cell and eight-cell mouse embryos and on their subsequent development during implantation.

Preimplantation mouse embryos were cultured for 48 hours from the four-cell and eight-cell stage to the blastocyst stage in the presence of cyclophosphamide (CPA) or one of its metabolites-4-hydroperoxy-CPA (4-HP-CPA), phosphoramide mustard (PAM), and acrolein (Acr)--to identify the metabolite which is embryotoxic after CPA treatment of pregnant mice during the preimplantation period. The dose-response relations for the inhibition of blastulation revealed identical inhibition curves for PAM and 4-HP-CPA (in solution 4-HP-CPA immediately decomposes to 4-hydroxy-CPA (4-OH-CPA)). These two metabolites are inhibiting blastulation in vitro at concentrations that are 10,000 times lower than CPA and 100 times lower than acrolein. When blastocysts which had developed in the presence of CPA and its metabolites in vitro were subsequently cultured in inhibitor-free medium NCTC-109, the same dose-response relationship pattern was obtained. Since 4-OH-CPA decomposes into acrolein and PAM in vivo and in vitro and since PAM and 4-OH-CPA exhibit identical embryotoxicity towards preimplantation embryos in vitro, PAM probably also is an active embryotoxic CPA metabolite in vivo before implantation. This result is discussed in relation to the importance of alkylating CPA metabolites in cancer treatment and in teratological studies during organogenesis.

Acrolein↗

PubMed2002

Bisphosphonates pamidronate and zoledronic acid stimulate osteoprotegerin production by primary human osteoblasts.

Bisphosphonates are potent antiresorptive drugs commonly employed in the treatment of metabolic bone diseases. Despite their frequent use, the mechanisms of bisphosphonates on bone cells have largely remained unclear. Receptor activator of nuclear factor-kappaB ligand (RANKL) is essential for osteoclast formation and activation, whereas osteoprotegerin (OPG) neutralizes RANKL. Various osteotropic drugs have been demonstrated to modulate osteoblastic production of RANKL and OPG. In this study, we assessed the effects of the bisphosphonates pamidronate (PAM) and zoledronic acid (ZOL) on OPG mRNA steady-state levels (by semiquantitative RT-PCR) and protein production (by ELISA) in primary human osteoblasts (hOB). PAM increased OPG mRNA levels and protein secretion by hOB by up to 2- to 3-fold in a dose-dependent fashion with a maximum effect at 10(-6) M (P < 0.001) after 72 h. Similarly, ZOL enhanced OPG gene expression and protein secretion by hOB in a dose-dependent fashion with a maximum effect at 10(-8) M after 72 h, consistent with the higher biological potency of ZOL. Time course experiments indicated a stimulatory effect of PAM and ZOL on osteoblastic OPG protein secretion by 6-fold, respectively (P < 0.001). Pretreatment with PAM and ZOL prevented the inhibitory effects of the glucocorticoid dexamethasone on OPG mRNA and protein production. Analysis of cellular markers of osteoblastic differentiation revealed that PAM and ZOL induced type I collagen secretion and alkaline phosphatase activity by 2- and 4-fold, respectively (P < 0.0001 by ANOVA). In conclusion, our data suggest that bisphosphonates modulate OPG production by normal human osteoblasts, which may contribute to the inhibition of osteoclastic bone resorption. Since, OPG production increases with osteoblastic cell maturation, enhancement of OPG by bisphosphonates could be related to their stimulatory effects on osteoblastic differentiation.

Biomarkers↗

PubMed1998

Phase I/II studies of isolated hepatic perfusion with mitomycin C or melphalan in patients with colorectal cancer hepatic metastases.

In an attempt to improve tumor response and survival among patients with colorectal cancer metastases confined to the liver, we developed an experimental (rats and pigs) and clinical isolated hepatic perfusion (IHP) technique to exploit maximally the steep dose-response relation of may anticancer drugs. In this overview we present our experimental and clinical results with mitomycin C (MMC) and melphalan (L-Pam). In rats, treatment with a four times higher maximally tolerated dose (MTD) of MMC during IHP compared to hepatic artery infusion (HAI) resulted in higher, more effective intratumoral concentrations of MMC. As a result, only in the IHP-treated rats were complete remissions observed and long-term survival achieved. Hepatotoxic side effects were minimal and transient in all animals. In the clinical phase I/II study with MMC 30 mg/m2 administered as a bolus in the isolated circuit, two of nine patients had a complete remission, with a median survival of 17 months. Four patients developed venoocclusive disease (VOD) of the liver, and as a result one patient died. Therefore we consider MMC unsuitable for further IHP studies. Meanwhile experiments in rats showed that IHP with the L-PAM MTD of 12 mg/kg was even more effective than MMC and did not cause hepatotoxic side effects. In the phase I/II dose-findings study with L-PAM in IHP, the MTD in humans was approximately 3.0 mg/kg. As in the rats, systemic toxicity was dose-limiting. The median survival of the whole group was 18 months. We have started a phase II study of L-PAM in IHP with a fixed dose of 200 mg L-PAM to determine if IHP can significantly increase the median survival and complete remission rate compared to other treatment modalities. Results from this study are expected by the end of 1997.

Animals↗

PubMed1986

Specificity of the generation and expression of enhanced anti-plasmacytoma immunity by spleen cells from melphalan-treated MOPC-315 tumor bearers.

We have shown previously that low-dose melphalan (L-PAM) therapy of mice bearing a large MOPC-315 plasmacytoma enables their hitherto immunosuppressed spleen cells to exert potent anti-MOPC-315 cytotoxicity following in vitro immunization with MOPC-315 tumor cells. Here we show that, following in vitro immunization with MOPC-315 tumor cells, spleen cells from such L-PAM-treated MOPC-315 tumor bearers exhibited enhanced T-cell-mediated cytotoxicity not only against the MOPC-315 tumor, but also against another plasmacytoma (MOPC-104E) possessing surface immunoglobulin (SIg) of a different idiotype than the MOPC-315 cells, as well as against a variant of the MOPC-315 tumor which does not produce nor possess SIg (SIg- MOPC-315). The enhanced cytotoxicity was directed against target antigens which are not expressed on the surface of the syngeneic WEHI 22.1 thymoma or the natural killer-sensitive YAC-1 cells. Plasmacytoma shared antigens, other than immunoglobulins, were able to stimulate spleen cells from L-PAM-cured MOPC-315 tumor bearers to generate in vitro a secondary type anti-plasmacytoma cytotoxic response. L-PAM-cured MOPC-315 tumor bearers exhibited in vivo immunity against SIg- MOPC-315 tumor cells, which was sufficiently triggered by the SIg- cells to bring about the rejection of a challenge of at least 100-fold the minimal lethal tumor dose of the SIg- MOPC-315 cells. Thus, SIg- MOPC-315 tumor cells present among SIg+ tumor cells in the parental MOPC-315 tumor inoculum can be eradicated in the L-PAM-treated MOPC-315 tumor bearers by the immune response to SIg+ tumor cells as well as by the immune response to SIg- tumor cells themselves.

Animals↗