Primary and secondary antibody responses to sheep erythrocytes of allogeneic bone marrow chimeras histocompatible at the left or right one-half of the H-2 complex.

Employing a new and reproducible method for allogeneic bone marrow transplantation, two kinds of irradiation chimeras were prepared. A/J mice treated with C3H/He marrow cells, which were designated [C3H leads to A/J], where donor and recipient were matched at left one-half of the H-2 complex showed significant numbers of plaque forming cells (PFC) following primary immunization with SRBC, a T-dependent antigen. In contrast [BALB/c leads to A/J] chimeras where donor and recipient were matched at right one-half of the H-2 were unresponsive to SRBC. These results are quite concordant with our previous observations in which B10 H-2 recombinant mice and AKR were used as bone marrow donor and recipient respectively. The vigorous antibody responses after the second stimulation with SRBC, however, were seen in either [C3H leads to A/J] or [BALB/c leads to A/J] chimeras. Direct PFC responses in [BALB/c leads to A/J] chimeras were slightly higher than those of [C3H leads to A/J] chimeras or normal control mice, while indirect PFC responses in [BALB/c leads to A/J] chimeras were low compared to those of the latter groups of mice. These findings suggest that there might be a delay in initiating the response and switching from IgM to IgG production in the chimeras where donor and recipient differed at the left one-half of the H-2.