Xid mouse lymphocytes respond to TI-2 antigens when co-stimulated by TI-1 antigens or lymphokines

Spleen cells from male (CBA/N x DBA/2) F1 hybrid mice do not significantly respond to in vitro stimulation by trinitrophenyl-conjugated polyacrylamide beads (TNP-PAA), whereas the same antigen elicits high PFC responses in female F1 hybrid cells. Therefore, this antigen could be classified as a T-independent type 2 (TI-2) antigen. When male spleen cells were co-stimulated by TNP-PAA and TI type 1 antigen, either LPS or Brucella abortus, they produced vigorous anti-TNP responses. A similar increase of the in vitro responsiveness of male F1 hybrid spleen cells to TNP-PAA antigen was provoked by the addition of supernatants from P 388-D1 cells stimulated by muramyl-dipeptide (MDP) mainly containing interleukin-1 (IL-1) or supernatants from phorbol 12-myristate 13-acetate (PMA)-stimulated EL-4 cells that contained T-cell factors. The PFC response to another TI-2 antigen, TNP-Ficoll, was also significantly enhanced after co-stimulation by P 388-D1 supernatants. The response to TI-2 antigens being macrophage dependent, the influence of supernatants of peritoneal macrophages from male and female F1 hybrids incubated with TNP-Ficoll on the PFC response of normal DBA/2 mouse spleen cells to sheep erythrocytes was assessed. It was found that macrophage supernatants from female hybrids regularly increased by more than two times this anti-SRBC PFC response, whereas macrophage supernatants from male F1 hybrids did not. Moreover, in a specific proliferation test measuring IL-1 activity, when macrophage supernatants from female F1 produced a 13-fold increase of thymidine incorporation, supernatants from male F1 only produced a three-fold increase. It is concluded that, in addition to the known defects of B cells from Xid mice, their macrophages are also defective.