PubMed Health⌕ Search

Biomedical subjects

H Rabin

Publications and source records attributed to H Rabin.

At least 37 records · Page 2Linked to original sources
PubMed1984

Characterization of exogenous type D retrovirus from a fibroma of a macaque with simian AIDS and fibromatosis.

A novel type D retrovirus was isolated by cocultivation of explants of fibromatous tissue from a rhesus monkey (Macaca mulatta) with immunodeficiency and retroperitoneal fibromatosis. This type D virus, isolated from a macaque with simian acquired immunodeficiency syndrome (SAIDS-D/Washington), is exogenous and is partially related to the Mason-Pfizer and the langur monkey type D viruses. The SAiDS-D virus can be distinguished from all other primate retroviruses by antigenicity and molecular hybridization. Nucleic acid hybridization studies reveal that the origin of the SAIDS-D isolate may reside in Old World monkey (subfamily Colobinae) cellular DNA.

Acquired Immunodeficiency Syndrome↗
PubMed1984

T-cell-mediated regression of "spontaneous" and of Epstein-Barr virus-induced B-cell transformation in vitro: studies with cyclosporin A.

The regression of Epstein-Barr (EB) virus-transformed B-cell outgrowth which is seen in experimentally-infected cultures of blood mononuclear (UM) cells from healthy seropositive donors can be abolished in medium containing the T-cell-suppressive agent cyclosporin A (CSA) at concentrations of 0.05 microgram/ml and above. CSA mediates its effect within the first 4 days post-infection of the UM cells and this prevents subsequent in vitro generation of the EB virus-specific cytotoxic-T-cell response which normally brings about regression. Regression can be fully restored by supplementing the CSA-treated culture with interleukin 2 (IL-2)-containing culture supernatants or indeed with purified IL-2 itself, suggesting that CSA mediates its effect in this system through inhibiting the endogenous production of IL-2 which is required to amplify the virus-specific cytotoxic response. "Spontaneous transformation" to EB virus genome-positive lymphoblastoid cell lines in noninfected cultures of UM cells from healthy seropositive donors, though rare in normal medium, is enhanced to such a degree in the presence of CSA that, for many donors, the phenomenon becomes titratable against input cell dose across the 2.0 X 10(6)-2.5 X 10(5) cells/culture range. Cell mixing experiments suggest that the spontaneously transformed cell lines which arise with such efficiency under these conditions do so not by direct in vitro outgrowth of progenitor cells transformed by the virus in vivo, but by a two-step mechanism involving virus release and secondary infection in vitro.

B-Lymphocytes↗
PubMed1984

Transformation of owl monkey T cells in vitro with Herpesvirus saimiri.

Owl monkey peripheral blood mononuclear cells were treated with phytohemagglutinin and expanded in interleukin 2 (IL-2)-containing medium. The cells were then exposed to Herpesvirus saimiri (HVS strain S295C)-infected owl monkey kidney monolayer cells. Four to 6 weeks later, the lymphocytes showed increased clumping and cell growth and the ability to grow in the absence of IL-2. Control lymphocyte cultures not exposed to HVS eventually died out at approximately 6-8 weeks, even in the presence of IL-2. Although infected lymphocytes grew continuously in the absence of IL-2, their growth was enhanced by addition of IL-2 to the cultures. Natural killer cell-like cytotoxicity and gamma-interferon release were also enhanced by IL-2. All cultures were positive for HVS antigens, infectious centers, or DNA. The reactivity of monoclonal antibodies to cell surface markers suggested that the resultant cell lines were comprised of activated T cells. The properties of the in vitro-transformed cells were similar to those of cells established from HVS-induced owl monkey tumors. Our results suggest that infection of T lymphocytes with HVS results in decreased dependence of T cells upon exogenous IL-2 for growth.

Animals↗
PubMed1984

Effects of natural and recombinant IL 2 on regulation of IFN gamma production and natural killer activity: lack of involvement of the Tac antigen for these immunoregulatory effects.

Highly enriched populations of human large granular lymphocytes (LGL), natural killer (NK) cells, and T cells were obtained from low and high density fractions, respectively, of discontinuous Percoll gradients. The NK cells were composed of 75 to 90% LGL, with the majority of the contaminating cells being monocytes. The T cells were greater than 95% OKT3+. The proliferative and cytotoxic progenitors in both fractions were examined by using a limiting dilution assay with interleukin 2 (IL 2) from four sources: 1) crude supernatant of a gibbon lymphoma (MLA-144), 2) purified (150,000-fold) MLA-144 IL 2, 3) partially purified human IL 2, and 4) purified recombinant human IL 2. The proliferative capacity was measured at day 7 by [3H]thymidine incorporation, whereas the progenitors of cells with NK-like activity were evaluated by assessing cytotoxic activity against K562 cells at day 8 in a 4-hr 51Cr-release assay. The frequency of proliferative progenitors among T cells was approximately 1/5 and was approximately 1/60 with LGL. Titration of the highly purified IL 2 preparation demonstrated that LGL proliferated with as little as 2 U of IL 2. The frequency of detectable cytotoxic progenitors in the LGL population, however, fell sharply when less than 40 U of IL 2 were employed. The T cells failed to demonstrate cytotoxic activity against the NK-susceptible target cells at any concentration of IL 2 tested. The IL 2 preparations also were examined for their ability to directly and rapidly enhance the cytotoxic activity of highly purified NK cells. All four preparations of IL 2 enhanced the cytotoxic activity of LGL without any detectable accessory requirement after incubation for as little as 6 hr, even though the MLA-144 IL 2 preparations were devoid of detectable interferons (IFN). These data indicate that IL 2 has dual effects on NK cells, regulating their activity was well as promoting their proliferation. Collectively, these results demonstrate that highly purified IL 2, devoid of other detectable lymphokines, is capable of supporting the growth of human NK cells and augmenting their in vitro activity. In parallel experiments, these same IL 2 preparations were quite active in causing the proliferation of T lymphocytes, clearly demonstrating a role of IL 2 in promoting the proliferation of NK cells as well as T cells. The mechanism of IL 2 boosting appears to be a direct interaction with LGL, resulting in the production of IFN gamma.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

Stimulation of immunoglobulin secretion in human B lymphocytes as a direct effect of high concentrations of IL 2.

In certain human IgM and IgG cell lines, immunoglobulin (Ig) secretion is highly stimulated by a B cell inducing factor (BIF) that is free of interleukin 2 (IL 2). BIF also induces Ig secretion in purified peripheral blood B cell populations that have been mitogenically stimulated by Staphylococcus aureus bacteria. Low concentrations of IL 2 (less than 20 U/ml) are not active in these systems. We now show that IL 2 at concentrations above 100 U/ml can induce Ig secretion in these blood B cells and B cell lines. Both conventional IL 2, purified from the human JURKAT and gibbon MLA-144 cell lines, and recombinant IL 2 are active. Very high concentrations approaching 10(4) U/ml are optimal for Ig secretion. Antibody to the T cell IL 2 receptor, anti-Tac, did not inhibit stimulation of the IgM cell line SKW6.4 by IL 2, and no Tac antigen was detected on the cells. The 9B11 monoclonal anti-IL 2 antibody that neutralizes T cell growth activity also abrogates stimulation of Ig secretion by conventional and recombinant IL 2 in the SKW6.4 cell line. However, the 1H11 monoclonal anti-(conventional thr3-glycosylated IL 2), which does not neutralize T cell growth activity, does inhibit induction of Ig secretion by the corresponding IL 2 in the B cell line. These results suggest that IL 2 stimulates B cells via a low-affinity interaction with a receptor different from the Tac receptor identified on T cells, and that the active site on the IL 2 molecule for B cells differs from that for T cell targets. If IL 2 promotes Ig secretion by binding with a low affinity to the B cell BIF receptor, IL 2 and BIF could be homologous proteins.

Animals↗
PubMed1983

Development of a serum-free medium which supports the long-term growth of human and nonhuman primate lymphoid cells.

The ability to grow lymphoid cells in serum-free media affords the advantage of separately analyzing those components found to be involved in proliferation and differentiation. Iscove's medium (IMDM) supplemented with bovine serum albumin or casein, cholesterol, ferrous chloride, insulin, beta-mercaptoethanol, L-alpha-phosphatidylcholine, and transferrin supported the long-term proliferation of a gibbon ape lymphoma T-cell line, MLA144. These cells continue to produce interleukin 2 (IL-2, T-cell growth factor) constitutively in the serum-free medium. IL-2-dependent human T cells initiated and maintained in culture in serum-free medium containing IL-2 have continued to replicate for over 3 months with two population doublings every 3 to 4 days. A normal, IL-2-dependent marmoset T-cell line, OH-1, also proliferated on the serum-free medium when supplemented with IL-2. Several established primate B-cell lines which do not require IL-2 for growth were able to proliferate in the serum-free medium. These B-cell lines included B95-8, an Epstein-Barr virus (EBV)-transformed marmoset cell line, HuCo/R-H, a human cord B-lymphocyte line transformed with EBV, and Namalwa, an EBV-positive B-cell line established from a Burkitt's lymphoma. B95-8 cells grown on serum-free medium showed high levels of EBV antigen-positive cells after induction with 12-O-tetradecanoyl-phorbol-13-acetate (TPA).

Animals↗
PubMed1983

Glycosylation pathways of two major Epstein-Barr virus membrane antigens.

Monoclonal antibodies to the Epstein-Barr virus (EBV) membrane antigens (MA) were used to delineate the sequence of events occurring during MA maturation. Immunoprecipitation experiments performed with B95-8 virus infected 1605L cells, pulse labeled in the presence of tunicamycin or 2-deoxyglucose, suggest that the nonglycosylated forms of the mature 236,000 (236K) and 86K MA have molecular weights of 149K and 69K, respectively. Monensin treatment results in the accumulation of a 189K antigen which is converted to the mature 236K MA after a 2 hr chase in the absence of monensin. Experiments with monensin also suggest that an 84K intermediate is involved in the formation of the mature 86K MA. The mature 236K MA is resistant to endoglycosidase H while the 189K intermediate and the mature 86K MA are partially sensitive to this enzyme. The mature 236K and 86K MA and the 189K intermediate are resistant to endoglycosidase D.

Antibodies, Monoclonal↗
PubMed1983

Identification of normal and transformed lymphocyte subsets of nonhuman primates with monoclonal antibodies to human lymphocytes.

Monoclonal antibodies (MAb) that detect specific lymphocyte subsets of man were tested for their reactivity with peripheral blood lymphocytes (PBL) and established cell lines of owl monkeys (Aotus trivirgatus) and marmosets (Saguinus spp). Results of these studies showed that certain determinants were conserved and that the pattern of reactivity observed in one genus (or even species) could not be used to predict the reactivity in another. On owl monkey PBL, reactivity equivalent to that on human PBL was observed with OKT11a, anti-Leu 3a, B1, and anti-HLA-DR MAb thus detecting T cell, helper/inducer T cell, B cell, and HLA-DR determinants. After neuraminidase treatment of owl monkey PBL, reactivity with anti-Leu 5 and OKT8 (T cell and suppressor/cytotoxic T cell determinants) was observed. Cell separation experiments indicated these determinants were found on lymphocytes with the same general properties as those of human origin. The use of these MAb to examine owl monkeys infected with Herpesvirus saimiri and tumor cell lines established from H. saimiri-inoculated monkeys revealed that the virus was found in OKT11a-positive, B1-negative cells. In chronically infected nondiseased animals, H. saimiri was found in anti-HLA-DR-negative cells and was restricted to anti-Leu 3a-positive cells (two animals) or was nearly equally distributed in anti-Leu 3a-positive and negative cells (one animal). Established H. saimiri tumor cell lines had the phenotype OKT11 a-positive, anti-HLA-DR-positive, B1-negative and were either anti-Leu 3a-positive or negative. Studies of interleukin 2-responsive tumor cells in short-term culture suggested the tumor was composed of virus-positive anti-Leu 3a-positive and negative populations.

Animals↗
PubMed1983

A rapid, large scale purification procedure for gibbon interleukin 2.

Interleukin 2 (IL 2) was purified from the conditioned medium of a gibbon T cell line, MLA144, which releases IL 2 constitutively. The IL 2 was obtained free of contaminating proteins by a simple process consisting of an initial batch purification on trimethylsilyl-controlled pore glass followed by reversed phase high pressure liquid chromatography. Overall recovery of IL 2 activity ranged from 70 to 100% of initial activity and yielded 2 X 10(6) or greater units of IL 2 per 15 liters of serum-free MLA144 conditioned medium. The specific activity of purified IL 2 ranged from 0.5 to 1 X 10(8) IL 2 U/mg protein. The purified IL 2 showed four molecular species when analyzed by two-dimensional isoelectric focusing-SDS-polyacrylamide gel electrophoresis. Each of the four molecular forms was active in the bioassay for IL 2 activity. Three molecular forms had apparent m.w. of 16,000 but different isoelectric points of 5.9, 6.3, and 6.7. One molecular form had an apparent m.w. of 15,000 and an isoelectric point of 7.2. The most abundant form of IL 2 had an apparent m.w. of 16,000 and an isoelectric point of 6.3. The purified IL 2 supported the growth of IL 2-dependent lymphocytes to a greater extent than did the same level of crude IL 2-containing MLA144 conditioned medium. The ability to purify large amounts of IL 2 by a rapid and efficient procedure will be of great help in both biochemical and immunologic studies of this lymphokine.

Amino Acids↗
PubMed1982

Discordant Epstein-Barr virus nuclear antigen (EBNA) antibody patterns in nasopharyngeal carcinoma.

Epstein-Barr virus nuclear antigen (EBNA) preparations from three sources were tested with sera from normal individuals and patients with Hodgkin's disease, breast carcinoma, Burkitt's lymphoma, and American and Chinese nasopharyngeal carcinoma. Individual sera with discordant antibody patterns were noted in all groups. Sera from both NPC groups gave significantly higher anti-EBNA titers on cell lines converted with P3HR-1 or B95-8 virus compared with anti-EBNA titers on Raji cells. Anti-EBNA titers of Chinese NPC sera showed no correlation among the three EBNA sources, while all other groups had highly correlated titers. Cross-absorption experiments present evidence for more than one antigenic determinant on EBNA. These results suggest an additional parameter for distinguishing Chinese NPC from other EBV-related disorders.

Antibodies, Viral↗
PubMed1982

Synthesis of biologically active interleukin 2 by Xenopus oocytes in response to poly(A)-RNA from a gibbon T-cell line.

The poly(A)-containing RNA isolated from a gibbon lymphosarcoma cell line, MLA144, known to release Interleukin 2 (IL2) was microinjected into Xenopus oocytes. The incubation medium from injected oocytes stimulated the DNA synthesis of an IL2-dependent cell culture and also maintained its viability. DNA-stimulating activity appeared in the oocyte incubation medium 6 h after injection and continued to accumulate for at least 96 h. Thymidine incorporation by the IL2-dependent cells is proportional to the concentration of oocyte incubation medium added and the IL2 activity produced by the oocytes is proportional to the amount of poly(A)-RNA injected. Incubation medium of oocytes injected with RNA from another T-cell line, 6G1, which does not produce IL2, did not contain DNA-stimulating activity. The same assay also showed that the IL2 mRNA sedimented at 14-16 S in a nondenaturing sucrose gradient. A series of monoclonal antibodies prepared against human IL2 neutralized the DNA-stimulating activity released by the injected oocytes to the same extent as they neutralized human IL2.

Animals↗
PubMed1982

Detection of antibodies to Epstein-Barr virus antigens by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) is described for the serologic analysis of antibodies to Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA), viral capsid antigen (VCA), and early antigen (EA). The specificity of each of the ELISAs was demonstrated by the use of well-characterized human sera shown by immunofluorescence assay to be variously reactive for antibodies to one or more of the three viral antigens studied. The ELISA for EBNA was four to 256 times more sensitive than immunofluorescence assays with all 33 EBNA-positive sera tested. The ELISAs for VCA and EA were also more sensitive than immunofluorescence assays: approximately 50% of the sera tested showed higher antibody titers. Sera that were negative for all three antigens by immunofluorescence assay were also negative by ELISA for each antigen. These ELISAs for EBV are rapid, sensitive, and objective and thus provide new and valuable methods for the detection of antibodies to EBV-related antigens.

Antibodies, Viral↗
PubMed1982

Surface markers of primate B and T lymphoid cell lines identified by antibodies to human and simian lymphocyte antigens.

Simian B and T lymphoid cell lines were shown to maintain surface markers found on mature lymphocytes in vivo. The T lymphoid cell lines expressed Ia-like antigens on their surfaces, further suggesting that they represent mature, activated T cells. These Ia antigens show a structural similarity to Ia on human cells although some diversity exists. The Ia antigen expressed on T lymphoid cell lines was shown to be very similar to those on B lymphoid cell lines. Owl monkey and marmoset T lymphoid cell lines were also shown to express a VH immunoglobulin-related determinant, a marker which is thought to be associated with T cell antigen receptor. Owl monkey and marmoset T cell lines express a surface antigen which identifies the sheep erythrocyte receptor on human T cells and some of these lines express an antigen found on human helper T cells. It is noteworthy that substantial conservation of surface components has occurred within primate evolution such that monoclonal antibodies to human Ia, OKT-11a and Leu 3a markers can be used to type lymphocytes of lower primates.

Animals↗
PubMed1982

Production and characterization of monoclonal antibodies against the Epstein-Barr virus membrane antigen.

Five murine hybridoma lines that produce monoclonal antibodies against Epstein-Barr virus membrane antigen (MA) were established. Immunoprecipitation experiments demonstrated that three of the antibodies precipitated both the 236,000 (236K) MA and the 212K MA. The other two antibodies precipitated the 86K MA. Antibodies against the 236K-212K MA and the 86K MA mediated complement-dependent cytolysis of Epstein-Barr-virus-infected cells. The antibodies against the 86K MA neutralized both the B95-8 and P3HR-1 viruses.

Antibodies, Monoclonal↗
PubMed1982

The effect of T cell growth factor on the cell cycle of primate T cells.

The effect of T cell growth factor (TCGF) on the cell cycle of four T cell lines that differed in their response to TCGF was studied. Activated normal marmoset T cells (OH-1) were totally dependent on the addition of TCGF for long-term proliferation. In the absence of TCGF, the cells were incapable of traversing the cell cycle and became arrested in G1. The addition of TCGF to arrested OH-1 cells stimulated them to enter the S phase after a lag phase of 24 to 33 hr. The TCGF-stimulated cells reached a maximum of cells in the S phase by 12 hr after the initiation of DNA synthesis. TCGF was required for a minimum of 18 hr before cells would enter the S phase. In the absence of TCGF, activated owl monkey (8I) and human (RG) lymphocytes displayed a TCGF-sensitive block; addition of TCGF stimulated these cells to enter the S phase after 12 and 16 hr, respectively. In contrast, an owl monkey tumor-derived T cell line (OMT-1), not dependent on exogenous TCGF for proliferation, was able to progress slowly through the cell cycle without a TCGF-sensitive block. These cells responded to TCGF by showing an initial increase in cells that entered the S phase after a lag of 6 hr and a continuing movement of additional cells into S over the course of the next several hours.

Animals↗
PubMed1981

Reactivity of monoclonal antibodies against human leucocyte antigens with lymphocytes of non-human primate origin.

The phylogenetic distribution of antigens present on human lymphocytes was investigated by incubating human or simian cells with murine anti-human monoclonal antibodies and then determining the level of reactivity with a radiolabelled anti-murine IgG reagent. The monoclonal antibodies used were specific for a T-cell antigen, lymphoid and lymphoid:myeloid antigens, Ia antigens, and beta 2 microglobulin. The cells examined included B- and T-lymphoblastoid cell lines and fresh peripheral blood lymphocytes separated by sheep erythrocyte rosetting into T-cell and non T-cell fractions. Results of these studies showed that the antibodies gave complete cross-reactivity with gorilla and chimpanzee cells while B-cell lines of orangutan origin had lost lymphoid and beta 2 microglobulin markers. Gibbon cells and cells of Old World and New World monkeys reacted strongly only with monoclonal antibodies against Ia antigenic determinants. These Ia antigens were found on the non T-cell fraction of fresh peripheral lymphocytes, on B-cell lines and on some virus induced T-cell tumour lines. Immunoprecipitation analysis using the anti-Ia antibodies showed a degree of molecular diversity on owl monkey and marmoset cells compared to the Ia antigens associated with human cells.

Animals↗