In vitro assays to study role of T cell-derived factors on human B lymphocytes should take into consideration inhibiting effect of large granular lymphocyte subset (CD5-,CD16+) that can contaminate B cell preparations.
In these studies, the inhibitory role of a large granular lymphocyte (LGL) subset (CD5-,CD16+) on pokeweed mitogen (PWM)-induced B lymphocyte differentiation was examined. CD5-,CD16+ LGL cells are the predominant subset of LGL cells and are possibly distinct from other LGL subsets in that they lack B and T cell markers. CD5-,CD16+ LGL possess abundant FcIgG receptors and previous studies have clearly demonstrated that in the presence of insoluble immune complexes, this LGL subset will inhibit B lymphocyte differentiation in the presence of T cells. In the present studies, we analyzed the inhibiting role of CD5-,CD16+ LGL cells that had not been activated by immune complexes. B + L preparations obtained by removal of E rosette-forming T cells were further depleted of T lymphocytes by complement-dependent lysis of T cells using a monoclonal antibody reactive to total T cells (Leu-1, CD5 antigen, Becton-Dickinson). B lymphocytes in such B + L preparations failed to differentiate into plasma cells containing intracytoplasmic immunoglobulin (Ig), in the presence of PWM, T cell-derived helper supernatants (THS), and interleukin-2 (IL-2). However, B cells differentiated under these conditions, when B + L preparations were further depleted of CD5-,CD16+ LGL cells by complement-dependent lysis using a monoclonal antibody (Leu-11) reactive to CD16 antigen of FcIgG receptors present on LGL cells. These studies indicated that CD5-,CD16+ cells unlike the CD8-positive T suppressor cell, will directly inhibit B lymphocyte differentiation into plasmacytoid cells containing intracytoplasmic Ig when T lymphocytes are not present. However, addition of a few T lymphocytes (less than 10%) to purified B + L preparations abrogated the CD5-,CD16+ LGL cell inhibition of B cell differentiation.
Lobo
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PI
Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville 22908.
Wright
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D000328:Adult; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001667:Binding, Competitive; D002450:Cell Communication; D002454:Cell Differentiation; D002469:Cell Separation; D002474:Cell-Free System; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D007694:Killer Cells, Natural / Q000145:classification / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D010641:Phenotype; D011043:Pokeweed Mitogens
D007376:Interleukin-2; D011043:Pokeweed Mitogens