Function of pokeweed mitogen-stimulated human T cells following vaccination with pneumococcal polysaccharides

The T cell regulation of pneumococcal polysaccharide (PPS)-specific B cells was investigated in pokeweed-mitogen (PWM)-stimulated cultures. The numbers of anti-PPS-secreting cells (SC) increased in cultures of mononuclear cells (MNC) established two weeks after the vaccination, as compared to cultures established before vaccination (from 18/10(6) MNC to 45/10(6) MNC). This finding was most likely explained by an increase in the blood of B-cell precursors with specificity for PPS. B cells spontaneously secreting anti-PPS were found only in cultures established one week after vaccination. However, the presence of PWM and T cells increased the numbers of anti-PPS-SC also in these cultures, indicating that not all PPS-specific B cells are fully differentiated in vivo one week after vaccination. The vaccination-induced changes in T cell function were investigated by recombining cryopreserved T cells or T helper cells (CD8 negative cells) with freshly isolated autologous B cells from post-vaccination day 15. The numbers of total Ig-SC in cultures containing day 13 T cells were significantly lower than the numbers in cultures containing day 0 T cells (3958/10(6) MNC versus 5887/10(6) MNC). The same tendency was observed for anti-PPS-SC; this difference, however, was not significant. No differences were observed in the ability of T helper cells to support the generation of total Ig-SC and anti-PPS-SC. Irradiation (2300 rad) of T cells from day 0 increased the numbers of anti-PPS-SC in the cultures significantly (three times), whereas irradiation of day 15 T cells did not have a significant augmenting effect.(ABSTRACT TRUNCATED AT 250 WORDS)