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Biomedical subjects

D Nelken

Publications and source records attributed to D Nelken.

18 recordsLinked to original sources
PubMed1990

Determination of surface bound and shed HLA antigens of amniotic cells by ELISA.

HLA typing of amniotic cells for clinical purposes using the conventional cytotoxicity assay is a laborious and complicated procedure. In the present study we demonstrate that HLA class I typing of the fetus can be determined using the enzyme linked immunosorbent assay (ELISA) either on amniotic cells or soluble free antigens shed by the cells into the culture medium. Our results indicate that the ELISA technique is a sensitive and reliable assay that can be used as an alternative method of HLA class I typing of amniotic cells.

Amniotic Fluid↗
PubMed1988

Differential expression of HLA class-I antigens on B and T lymphocytes obtained from human lymphoid tissues.

The amount of HLA class-I antigens was determined on the surface of enriched populations of B and T lymphocytes obtained from human peripheral blood, lymph nodes and spleens. The assays were performed using monoclonal antibodies that recognize different determinants on HLA class-I antigens and utilizing a simple and sensitive enzyme-linked immunosorbent assay (ELISA). Our results indicate that B lymphocytes obtained from human peripheral blood, lymph nodes and spleens express at least twice as many HLA class-I antigens as T lymphocytes obtained from the same organs.

Antibodies, Monoclonal↗
PubMed1987

Human leukocyte antigens (HLA) class I and class II on sperm cells studied at the serological, cellular, and genomic levels.

The expression of human leukocyte antigens (HLA) on highly purified human ejaculated sperm cells was studied using the sensitive enzyme-linked immunosorbent assay (ELISA) technique and a wide panel of monoclonal antibodies to class I and class II HLA. In addition, the stimulatory capacity of these cells was tested in mixed cultures of lymphocytes and spermatozoa, and the levels of RNA homologous to the HLA class I and class II genes were determined. The results obtained using the ELISA indicate that the class I and class II HLA serologically defined antigens are weakly expressed on the cell surface of the mature spermatozoa. Highly purified sperm cells consistently stimulated heterologous lymphocytes but not when HLA-DR compatibility was observed between stimulator and responder. The proliferative response of lymphocytes induced by sperm cells was lower than the response obtained in a lymphocyte-lymphocyte combination, though the kinetics of the response were similar in both cases. In addition, it was found that spermatozoa contained RNA species homologous to HLA class II DR beta and DQ beta genes sequences but not to HLA class I sequences. The levels of these RNA species were significantly reduced after interferon stimulation. Lymphocytes that served as positive control were found to contain RNA complementary to both HLA class I and class II genes.

Antibodies, Monoclonal↗
PubMed1979

Normal immunosuppressive protein inhibition of human and murine lymphoblastoid cell line proliferation.

Normal immunosuppressive protein, prepared from human plasma by DEAE-cellulose chromatography, inhibits DNA synthesis in human cell lines of lymphocytes of both T and B origin. It also inhibits [3H]thymidine incorporation in mouse cell lines. Normal immunosuppressive protein was able to inhibit the proliferation of these cells, although they were already transformed and had a high rate of DNA synthesis. On the other hand, it does not inhibit myeloid cells or fibroblasts.

Alpha-Globulins↗
PubMed1979

Normal immunosuppressive protein purification and quantitative estimation experiments.

An improved method for the preparation and purification of normal immunosuppressive protein (NIP) is described. The purified material has a molecular weight between 10,000 and 25,000. Its biological and serological activity is approximately 10--20 times higher than that of the crude fraction. An antibody to normal immunosuppressive protein prepared in rabbits made the quantitative estimation of NIP by a haemaggluination inhibition test possible. Similarly, a very sensitive assay for the quantitative determination of NIP by its inhibitory effect on the proliferation of EL-4 tumor cells is also described. Eluates prepared from polyacrylamide gels were active in inhibiting EL-4 tumor cell proliferation and neutralized the anti-NIP activity in the haemagglutination inhibition test.

Animals↗
PubMed1979

Normal immunosuppressive protein: in vitro inhibition of DNA synthesis in T and B lymphocytes and lymphoid cell lines.

The biologic activity of normal immunosuppressive protein (NIP) isolated from human plasma was studied. NIP was found to inhibit the proliferation of both T and B lympohcytes in vitro. It suppressed the DNA synthesis of normal mouse lymphocytes responding to the mitogens phytohemagglutinin and lipopolysaccharide, as well as the [3H]Thymidine and [3H]leucine uptake by T and B lymphoid cell lines of human and murine origin. The lymphoid specificity of NIP was demonstrated by showing that DNA and protein synthesis of normal and transformed fibroblasts and other nonlympohid cell lines was not affected by NIP treatment. Furthermore, by using lymphoid cell lines we were able to show that 1) NIP inhibits the process of ongoing DNA and protein synthesis; 2) the duration of the cells' exposure to NIP is crucial for obtaining optimal effect; and 3) the inhibitory effect of NIP is totally reversible.

Animals↗
PubMed1978

Normal immunosuppressive protein: inhibitory effect on immune response against tumour cells.

Normal immunosuppressive protein isolated from human plasma was found to inhibit the generation of primary cytotoxic effector lymphocytes against allogeneic tumour cells in vitro. Total inhibition was observed when NIP was present during the early stages of the sensitization process. In contrast, the generation of secondary cytotoxic lymphocytes in vitro was only slightly inhibited even though large amounts of NIP were used. The inhibition of target cell lysis by sensitized lymphocytes required long preincubation of a relatively small number of effector cells with large amounts of NIP and was most significant when tested at low effector: target cell ratios. Under the same conditions NIP showed no inhibitory effect on the cytotoxic activity of immune macrophages. The present in vitro experiments suggest that NIP exerts its effect through inhibition of DNA synthesis and cellular proliferation and to a limited extent only, by inducing specific suppressor cells.

Alpha-Globulins↗
PubMed1977

HLA B27 and ankylosing spondylitis in the Israeli population.

The distribution of 24 HLA antigens of the A and B loci was investigated in 38 Israeli ankylosing spondylitis (AS) patients of various ethnic origins. This was compared with the distribution in rheumatoid arthritis (RA) and osteoarthritis (OA), as well as in 456 controls representing the Jewish population and 260 controls representing the Arab population. Included in the study were Ashkenazi Jews and non-Ashkenazi Jews, as well as Moslem and Christian Arabs. The frequency of HLA B27 among AS patients (79 per cent) was significantly greater (P less than 10(-10)) than among the controls (three per cent). Ashkenazi Jews showed a higher relative risk than non-Ashkenazi Jews and Arabs. Six of the AS patients were offspring of consanguineous marriages, but this was not higher than expected and therefore no indication for rare recessive genes contributing to the disease could be demonstrated. This study confirms the association between AS and B27, and extends our knowledge to the heterogeneous population of Israel not previously investigated. A significant but weak association of B27 with RA was noted. No correlation of other HLA antigens with RA or OA was observed.

Adult↗
PubMed1977

Islet of Langerhans allotransplantation in the rat.

Normoglycemia in rats allotransplanted with islets of Langerhans was studied. It was found that pretreatment with donor liver extract and pertussis followed by a short course of ALS treatment results in much better overall survival of functioning islets of Langerhans allotransplants than with other forms of immunosuppression tested.

Animals↗
PubMed1975

Inhibition of T- and B-lymphocyte functions by normal immunosuppressive protein.

Normal immunosuppressive protein (NIP) isolated from human plasma was studied in two well defined systems. (1) Spontaneous rosettes of sheep red blood cells with human peripheral blood lymphocytes and PHA-induced lymphocyte cytotoxicity as indicators for T-cell function. (2) Rosette formation tests of human lymphocytes with antibody-coated erythrocytes or erythrocytes coated with antibody and complement as well as antibody-induced lymphocyte-mediated cytotoxicity represented non-T-cell activity. While NIP did not inhibit the formation of any of the above mentioned rosettes, it practically prevented both PHA-induced and antibody-mediated lymphocyte cytotoxicity. Relatively small amounts of NIP inhibited PHA-induced cytotoxicity while higher doses were required for the inhibition of antibody-mediated lymphocyte cytotoxicity. Possible mechanisms of its suppressive activity are discussed. NIP was found to be heat-stable and did not show any species specificity, as NIP preparations from human plasma were immunosuppressive in human, mouse and guinea-pig systems.

Alpha-Globulins↗