Limited T helper cell activity in C57BL/10 (B10) mice with inherited low IgG responsiveness.

Due to limitations in antigen processing, mice of the C57BL/10ScSn (B10) strain exhibit a low IgG production against a variety of T-dependent antigens. To characterize the T-cell functions, the authors studied antigen-specific T-cell proliferation and cytokine production in vitro. The response of B10 mice was compared with that of the high IgG producing strain A/J. A highly restricted proliferative response and almost no interleukin-2 (IL-2) and interleukin-3 (IL-3) production was detected in lymph node (LN) cells of B10 mice primed in vivo by protein antigens and subjected to a specific restimulation in vitro, whilst A/J cells responded by significant proliferation and cytokine production. The antigen-specific T-cell response of B10 mice could not be increased by lipopolysaccharide treatment in vivo or by in vitro cultivation with IL-2. However, the T cells of B10 mice produced high levels of IL-2 and IL-4 when stimulated by phorbol myristate acetate (PMA) and Ca2+ ionophore, proving the existence of a functionally intact signal transduction pathway downstream of protein kinase C (PKC). The results suggest that the in vivo antigen priming does not effectively activate the T cells in B10 mice. The limited activation consequently leads to the low IgG response described in B10 mice.