EFFICIENCY OF INDUCTION OF IMMUNOGLOBULIN-SYNTHESIS BY AUTOLOGOUS HUMAN T-CELLS AND T-CELL CLONES - RELATION TO SURFACE ISOTYPE OF THE B-CELL

Efficient immunoglobulin (Ig) production was induced when human B cell s were cultured with autologous T cells activated by immobilized CD3 m Ab in cultures supplemented with IL-2. Negatively purified B cells or B cells positively selected with mAb to CD19, CD21 or CD72 surface ant igens produced IgM, IgG and IgA, whereas B cells selected for surface IgD or IgM produced predominantly IgM indicating that little or no iso type switching was occurring. Results are compared with reports descri bing high levels of mu to gamma and mu to alpha switching in single B cell systems. The limited proliferation of B cells in our culture syst em may account for the difference. When untreated T and B cells were c ultured together in the presence of immobilized CD3 mAb, B cell number s peaked at 6-10 days whereas T cells continued to proliferate maximal ly. All 52 T cell clones tested induced the production of IgM, IgG and IgA from unselected or CD19 selected B cells, but efficiency of produ ction of Ig overall and of the different isotypes varied with differen t T clones. All T clones which induced high IgM, IgG and IgA productio n induced IgE production too, but some less active T clones also induc ed IgE production under non-switching conditions indicating that direc t contact with activated T clone cells efficiently induces IgE as well as IgG and IgA production from B cells already expressing these isoty pes. Less Ig was produced with optimal numbers of untreated T clone ce lls than with X-irradiated cells, confirming that proliferating T cell s can inhibit as well as activate Ig production from B cells.