Characterization of a T4+/Leu-8+ T cell clone that directly helps B cell Ig production by secreting B cell differentiation factor.
A human T4+/Leu-8+ T cell clone (YA2) was established by phytohemagglutinin activation and interleukin 2 (IL 2) propagation. Functional characterization of this clone demonstrated that it provided potent help towards Ig production by pokeweed mitogen-stimulated B cells in the presence of small numbers of autologous T cells or by Staphylococcus aureus Cowan I (SAC)-activated B cells in the presence of B cell growth factor (BCGF). YA2 provided no help to resting B cells and minimal help to either unactivated B cells cultured with BCGF or SAC-activated B cells. Supernatant generated from clone YA2 by IL 2 stimulation had significant B cell differentiation activity but no BCGF or IL 2 activity. Thus, YA2 is a T4+/Leu-8+ potent direct helper only to B cells that are activated and proliferating due to its selective secretion of a differentiation factor, and not an activation and growth factor. The availability of phenotypically defined cloned populations of T cells with restricted functional helper activity related to the secretion of selected B cell tropic factors should prove useful in the dissection of the role of individual T cell subsets in the regulation of the human B cell cycle.
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D001402:B-Lymphocytes / Q000378:metabolism*; D002999:Clone Cells / Q000145:classification / Q000276:immunology / Q000378:metabolism; D006133:Growth Substances / Q000096:biosynthesis* / Q000494:pharmacology; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis*; D015847:Interleukin-4; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation / Q000528:radiation effects; D008222:Lymphokines / Q000096:biosynthesis* / Q000494:pharmacology; D010641:Phenotype; D013601:T-Lymphocytes / Q000145:classification* / Q000378:metabolism / Q000528:radiation effects
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006133:Growth Substances; D007136:Immunoglobulins; D008222:Lymphokines; D015847:Interleukin-4