3 FUNCTIONALLY DISTINCT HELPER T-CELL CLONES - THE ROLES FOR ANTIGEN NON-SPECIFIC HELPER FACTORS IN B-CELL ACTIVATION THROUGH 2 DIFFERENT PATHWAYS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 56  (4) , 585-596
Abstract
We established three functionally distinct purified protein derivative (PPD)-reactive T-cell clones (B11.15, B12.F and D-2). Clone B11.15 could co-operate with DNP-primed B cells to induce anti-DNP IgG plaque-forming cell (PFC) responses only when high amounts of PPD were added to the culture whereas stimulation of a low amount of DNP-PPD was ineffective (factor-mediated interaction). On the other hand, clone D-2 activated those B cells in a MHC-restricted manner only when DNP-PPD was added to the culture (cognate interaction). B12.F could stimulate B cells with either PPD or DNP-PPD. Antigen non-specific helper factors (lymphokines) responsible for B-cell activation produced by cloned T cells upon stimulation with PPD and antigen-presenting cells were then investigated. Lymphokine activities determined in the present study were IL-2, BCGF I, BCGF II and TRF. BCGF I activity was determined by proliferation-inducing activity on purified B cells in the presence of anti-IgM antibody. BCGF II activity was measured by proliferation-inducing activity on purified B cells in the presence of dextran sulphate. TRF activity was determined on DNP-primed B cells for inducing further differentiation into anti-DNP IgG PFC. BCGF I active molecules were eluted in the fraction at apparent MW of 50,000-70,000 and 8,000-10,000 in gel-permeation column chromatography. BCGF II active molecules were recovered in the fractions at an apparent MW of 30,000-45,000. In addition, it was demonstrated that BCGF I acted on both activated and resting B cells. In contrast, BCGF II acted on blasted B cells. In contrast, BCGF II acted on blasted B cells but not resting B cells. TRF was hardly separable from the BCGF II active one on gel permeation column chromatography. In the comparative analysis of lymphokine activities in supernatants obtained from three functionally distinct T-cell clones stimulated by antigen, clone B12.F was the highest producers of all kinds of lymphokines tested. Clone B11.15 produced IL-2, BCGF II and TRF. However, BCGF I was hardly detectable in cell-free supernatants of B11.15. Clone D-2 produced relatively far less amounts of lymphokines except for IL-2. IL-2 was produced by all three T-cell clones. The results suggest that multiple lymphokines are involved in B-cell activation through factor-mediated T-B cell interaction. Moreover, our data suggest that lymphokines such as BCGF I, BCGF II or TRF do not play important roles in B-cell activation through cognate T-B cell interaction.

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