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Biomedical subjects

S D Litwin

Publications and source records attributed to S D Litwin.

At least 55 records · Page 3Linked to original sources
PubMed1976

Change in Ig expression of a human lymphoblastoid line during long-term culture.

A human lymphoblastoid line, in continuous culture for over 3 years, showed changes in Ig expression with time. The following pattern of events was suggested by studies of Ig synthesis and secretion performed at intervals. In a mass culture containing a heterogeneous cell population, Ig expression may shift because of selection acting on the different phenotypes. In human lymphoblastoid lines there may be a tendency for selection to favor IgMchi-producing cells. In clones, including those that synthesize multiple H chains, substantial determinism for Ig expression is present.

Cell Line↗
PubMed1976

Synthesis of Gm allotypes by human tonsillar lymphocytes in culture: concordance with serum phenotype.

Isolated human tonsillar lymphocytes were cultured with pokeweed mitogen, phytohemagglutinin, and without mitogen for 9 to 28 days. IgK, Gm(a) and Gm(f) were then quantitated in the cell suspensions. In cultures of cells derived from persons whose blood was heterozygous for IgGl allotype antigens Gm(a+f+), approximately equal amounts of Gm(a) and Gm(f) were found. In cultures of cells of Gma or Gmf homozygotes, there was complete concordance between the Gm allotype antigens produced by the cultures and the donor's serum phenotype-with no instance, either at zero time or at culture termination in which a Gm antigen was detected which was absent from the donor's serum. It was concluded that in vitro genetic allotype synthesis in tonsillar lymphocytes during short-term culture mirrored accurately in vivo Gm expression. IgK and Gm antigen synthesis was highest in the flasks containing pokeweed mitogen although both phytohemagglutinin and no-mitogen control flasks showed, in certain experiments, proliferation and an increase in the Ig per viable cell. It was observed that no-mitogen flasks contained twice as much allotype antigen as did phytohemagglutinin flasks suggesting an inhibition of Ig synthesis associated with the mitogen. The tonsillar lymphocytes, under the experimental conditions employed, were shown by a radio-incorporation and immunoprecipitation technique to be synthesizing polyclonal Ig de novo, at the termination of the cultures.

Cells, Cultured↗
PubMed1975

A glycoprotein associated with the membrane fraction of human B but not T lymphocytes.

A method is described which employs differential centrifugation and sucrose density gradient centrifugation to isolate a membrane fraction from human lymphocytes. Membrane preparations from long-term human cultured B- and T-lymphoid lines, peripheral blood lymphocytes, tonsillar lymphocytes, and thymocytes were analyzed on 0.5% sodium dodecyl sulfate-7.5% polyacrylamide gels stained for protein and carbohydrate. The most important finding was a major glycoprotein of approximately 30,000 daltons associated with the membrane preparations from B lymphocytes. T-lymphocyte preparations did not contain readily detectable amounts of this membrane-associated component. The T-cell lymphoid line MOLT-4 was unique in that it had a narrow protein band at approximately 30,000 daltons which did not contain carbohydrate.

Antigens↗
PubMed1975

Abnormal immune responses of Bloom's syndrome lymphocytes in vitro.

Bloom's syndrome is a rare autosmal recessive disorder, first characterized by growth retardation and asum-sensitive facial telangiectasia and more recently demonstarted to have increased chromosome instability, a predisposition to malignancy, and increased susecptibitily to infection. The present report ocncern the immune function of Bloom's syndrom lymphoctes in vitro. Four affected homozgotes and five heterozygotes were studied. An abnormal serum concentartion of at least one class of immunoglobin was present in three out of four homozgotes. Affected homozgotes were shown capable of both a humoral and cellular response after antigenic challenge, the responses in general being weak but detectable. Blood lymphocytes from Bloom's syndrome individuals were cultured in impaired proliferavite response and synthesized less immunoglobulin at the end of 5 days than did normal controls. In contrast, they had a normal proliferative response to phytohemagglutinin except at highest concentrations of the mitogen. In the mixed lymphocte culture, Bloom's syndrome lymphocytes proved to be poor responder cells but normal stimulator cells. Lmyphoctes from the heterozgotes produced normal responses in these three systems. Distrubed immunity appears to be on of several major consequences of homozygosity for the Bloom's syndrome gene. Although the explanation for this pleiotropism is at present obscure, the idea was advanced that the aberrant immune function is, along with the major clincial feature-small body size, amanifestation of defect in cellular proliferation.

Abnormalities, Multiple↗
PubMed1973

Characterization of cystic fibrosis factor and its interaction with human immunoglobulin.

Cystic fibrosis factor activity (CFFA), assayed as the ability to stop oyster ciliary movement, was present in serum-free medium from actively growing cystic fibrosis skin fibroblast cultures. CFFA was associated with a low molecular weight, negatively charged molecule that contained no uronic acid and was heat and pH labile. When CFFA-positive media were mixed with human IgG1, the CFFA was chromatographically displaced and emerged with the IgG1 fraction on column chromatography. Experiments in which various immunoglobulins were added to CFFA-positive culture media and then incubated with specific anti-immunoglobulins suggested that CFFA binding was class specific for human IgG, subclass specific for IgG1 and IgG2, and occurred with intact unaggregated heavy chains but not with kappa- and lambda-light chains, or Fab, Fc, and F(ab')(2) fragments. The serum protein beta(2)-microglobulin, which has structural homology to IgG, also bound CFFA.

Age Factors↗
PubMed1973

The relationship between 2 -microglobulin and immunoglobulin in cultured human lymphoid cell lines.

beta(2)-microglobulin was detected on the cell surface and in the medium of human lymphoid cells established in long-term culture. The secretion of beta(2)-microglobulin was relatively uniform when different cell lines were compared, whereas IgG production varied widely. kappa- and micro-membrane antigens were modulated by specific antibody; beta(2)-microglobulin was not modulated. Anti-kappa and anti-micro antisera had no effect on the expression of membrane beta(2)-microglobulin, nor had anti-beta(2)-microglobulin antiserum any effect on the expression of kappa- and micro-membrane antigens.

Animals↗