Potentialities of immunocompetent cells in high and low antibody-producing lines of mice obtained by selective breedings for responsiveness to flagellar or somatic antigens of Salmonellae.

The genetic modifications of immunocompetent cell functions were investigated in high (H) and low (L) antibody responder lines of mice obtained by selective breeding for responsiveness to flagellar and somatic antigens of Salmonellae (Selection III and Selection IV, respectively). Several lines of evidence converge to demonstrate that the differences in antibody responses between the H and L lines of the two selections are not due to the modification of antigen handling by macrophages. This contrasts with previous observations that macrophages play a major role in interline differences in Selections I and II. The choice of antibody titres after secondary challenge as the phenotypic character in Selections III and IV may explain why the regulatory role of macrophages was minimized, compared with Selections I and II which were carried out for primary responses to heterologous erythrocytes. In Selections III and IV, H mouse lymphocytes were more efficient than L mouse lymphocytes in restoring immunoresponsiveness to irradiated hosts. In contrast, allogeneic skin grafts were rejected at a similar rate in L as well as in H mice of the two Selections and in vitro lymphoproliferative responses to T cell mitogens were also equivalent in the four lines.