Protection of newborn mice from graft versus host disease by maternal pre-immunization.

Alloimmunization of BALB/c (H-2d) female mice with allogeneic spleen cells from C57BL/6 (H-2b) or CBA/H (H-2k) mice protects BALB/c offspring from graft-versus-host disease (GVH-D) following neonatal intraperitoneal inoculation of high doses of spleen cells respectively of C57BL/6 or CBA/H strains of mice. The mice survived GVH-D over one year after the allogeneic inoculum 24-48 h after birth and they did not show any signs of GVH reaction nor splenomegaly. We show that this phenomenon is antibody mediated and affects the developing immune system of the foetus. Repeated immunization of virgin female BALB/c with anti-H-2b or anti-H-2k antisera (Ab1) can equally abrogate GVH-D in their newborn offspring challenged at 24-48 h after birth with allogeneic spleen cells of H-2b or H-2k phenotype. Our results demonstrate that protection from GVH-D is not specific to the immunizing strain and occurs when the neonatal mice are challenged with C57BL/6 or CBA/H spleen cells. There is thus crossreactivity of tolerance against H-2 specificities. In this study we also report on the in vitro cellular immune responses of the surviving GVH-resistant mice and demonstrate that these responses against both the challenge and third party lymphocytes are impaired.