Immune response gene control of antibody specificity

The expression of the histocompatibility-linked PLL Ir gene was investigated in guinea pig B cells. Strain 2 and F₁ (2 × 13) guinea pigs, immunized with the αDnp-Lys₉, produce both T cells and antibody which are equally discriminatory for αDnp-Lys₉. In contrast strain 13 (PLL Ir gene negative) guinea pigs immunized with αDnp-Lys₉ do not develop specific T-cell responses and the antibody produced while restricted in heterogeneity cannot differentiate the immunizing antigen from Dnp-OH. However, if in a F₁ (2 × 13) environment, PLL Ir gene-negative B cells are provided with F₁ (2 × 13) T cells they express the ability to make antibody as specific and discriminatory as the antibody produced by PLL Ir gene-positive B cells. These findings strongly suggest that in the guinea pigs the PLL Ir gene defect is localized to the T cells and that the repertoire of specificity of B cells is similar if not identical in both responder and nonresponder animals. In addition these observations support the notion that the cellular locus for the PLL Ir gene expression in the guinea pigs is limited to T cells and not to macrophages and B lymphocytes.