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F D Finkelman

Publications and source records attributed to F D Finkelman.

242 records · Page 14Linked to original sources
PubMed1978

Control of human B lymphocyte responsiveness: enhanced suppressor T cell activity after in vitro incubation.

Human peripheral blood mononuclear cells (PBM) lost the capacity to generate immunoglobulin-secreting cells (ISC) in response to pokeweed mitogen (PWM) after a period of preincubation in vitro. When fresh PBM were co-cultured with preincubated PBM their response to PWM was inhibited, indicating that enhanced suppressor activity developed in the aged PBM concomitant with the loss of PWM responsiveness. Suppressor cell activity of aged PBM was present within the T lymphocyte population. The suppressor T cell inhibited PWM responsiveness of autologous and homologous PBM to an equivalent degree. The action of the suppressor cell was abrogated by inhibitors of DNA synthesis or by hydrocortisone. A suppressor T cell population with similar characteristics was found in freshly prepared PBM before in vitro incubation. Expansion of this suppressor T cell population during preincubation required cell division. There was no change in the functional capability of the helper T cell population as a result of similar in vitro culture. These observations indicate that a T cell population capable of suppressing PWM-induced generation of ISC can be selectively expanded by in vitro incubation of normal human PBM without additional mitogenic stimulation. Moreover, these data emphasize that control of B lymphocyte differentiation involves a critical interrelationship between T lymphocyte subpopulations exerting both positive and negative influences.

Antibody-Producing Cells↗
PubMed1978

Immunoglobulin secretion by human splenic lymphocytes in vitro: the effects of antibodies to IgM and IgD.

The effects of F(ab')2 fragments of affinity-purified rabbit anti-human mu chain antibody (RaHmu) and rabbit anti-human delta chain antibody (RaHdelta) on spontaneous and mitogen-stimulated immunoglobulin (Ig) secretion by normal human spleen cells were studied. IgM and IgG secretion by human spleen cells cultured in vitro was measured by incubating the cells with 3H-amino acids precipitating the secreted labeled Ig with anti-Ig, and analyzing the precipitates by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Both RaHmu and RaHdelta suppressed spontaneous and LPS-induced IgM and IgG secretion as well as PWM-stimulated IgG secretion. In different experiments, RaHmu and RaHdelta either suppressed or augmented PWM-induced IgM secretion. The anti-Ig induced augmentation of PWM-triggered IgM secretion was most apparent when spleen cells were cultured at lower cell densities or when lower concentrations of anti-Ig were employed. These date indicate that perturbation of B cell surface immunoglobulin receptors with specific anti-Ig antibody can alter markedly the ability of these cells to differentiate into antibody-secreting cells.

Animals↗
PubMed1976

Cell membrane IgD: demonstration of IgD on human lymphocytes by enzyme-catalyzed iodination and comparison with cell surface Ig of mouse, guinea pig, and rabbit.

A substantial fraction of human cord blood and peripheral blood lymphocytes have recently been shown to bear IgD. Although IgD has not been identified in mice, it has been suggested that it is also a major surface immunoglobulin of murine lymphocytes. Thus, lactoperoxidase-catalyzed iodination of surface immunoglobulin of mouse spleen and lymph node cells reveals the existence of an IgH chain differing from mu, gamma, and alpha-chain both antigenically and by mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This new H chain class has been previously proposed to be the mouse homologue of delta-chain. In this paper, we analyzed human, mouse, guinea pig, and rabbit lymphoid cell membrane Ig by lactoperoxidase-catalyzed iodination, extraction with non-ionic detergent precipitation with a variety of specific anti-Ig sera, and electrophoresis of dissolved reduced precipitates on sodium dodecyl sulfate-polyacrylamide gels. Our studies confirm the previous reports of a new mouse cell membrane H chain with a mobility more rapid than that of mu-chain. However, we fail to detect a molecule with this electrophoretic mobility on the surface of guinea pig or rabbit lymph node and spleen cells. Moreover, neither anti-kappa nor anti-delta antibody precipitates a molecule with an H chain of this mobility from labeled extracts of human cord blood or peripheral blood lymphocytes. Cell surface delta was identified on both human cord blood and peripheral blood lymphocytes, but it proved to have mobility similar to human and mouse mu-chain. This result indicates either that mouse delta-chain has an electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels which differs appreciably from that of human membrane delta-chain or that the newly described mouse H chain is not the homologue of human delta-chain.

Animals↗
PubMed1975

Abnormal ratio of membrane immunoglobulin classes in mice with an X-linked B-lymphocyte defect.

CBA/N mice have an X-linked genetic defect in B-lymphocyte function manifested by inability to make antibody responses to T-independent antigens. Plasma membrane immunoglobulin (Ig) on spleen, lymph node, and Peyer's patch cells was analyzed by lactoperoxidase-catalyzed iodination, NP-40 extraction, specific immunoprecipitation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These studies indicated that the X-linked immune defect was associated, in all three cell types, with a decrease in the ratio of cell membrane IgD analog to cell membrane IgM. This suggests either that IgD analog may be important in initiation of T-independent antibody responses or that CBA/N mice lack a subpopulation of B cells specialized to respond to T-independent antigens, and that these cells are relatively rich in plasma membrane IgD analog.

Animals↗
PubMedDate not supplied

Augmented in vitro presentation of Mls determinants after anti-immunoglobulin-induced B cell activation: ontogeny and role of purified B cells.

Murine splenocytes which contained B cells activated by in vivo exposure to affinity-purified goat anti-mouse IgD (GaMD) antibody were utilized to present major histocompatibility complex (MHC) and non-MHC minor lymphocyte-stimulating (Mlsa) determinants in a primary mixed lymphocyte reaction (MLR). As the time in hours after in vivo exposure to GaMD increased, splenocytes from adult mice showed a co-ordinate increase in cell size, expression of public and private MHC class II antigenic determinants and MHC and Mlsa antigen-presenting capacity. This augmented alloantigen-presenting capacity was demonstrable with either irradiated or mitomycin C-treated adult splenocytes. In contrast, GaMD-treated neonatal splenocytes from 10-day-old mice demonstrated no significantly increased class II expression or enhanced MHC stimulatory capacity, but nevertheless triggered augmented responder cell proliferation across an Mlsa barrier. Thus, increased class II expression or presenting capacity may not be required for an augmentation in splenocyte Mls-stimulating ability to occur. In vitro exposure of T cell-depleted splenocytes or highly purified small resting B cells to GaMD or lipopolysaccharide (LPS) induced a substantially increased ability in those populations to present MHC and Mlsa antigens in a primary MLR. Hence in vivo or in vitro activation of B lymphocytes in a stimulator cell population may yield more effective presentation of MHC and non-MHC determinants.

Animals↗