Cell & Tissue Transplantation & Therapy

Understanding the immune response is critical to evaluate the response to infection and vaccines, particularly in bone marrow transplant (BMT) recipients who may exhibit an altered immune system. Such studies have relied upon inbred mouse models due to genetic consistency and experimental reproducibility. Recent studies suggest that inbred mice vary substantially from outbred counterparts in terms of immune responses. These experiments quantified differences in immune responses of inbred and outbred mice before and after BMT. Inbred and outbred adult mice were lethally irradiated and syngeneic bone marrow transplants performed. 6–9 weeks after engraftment, the mice were immunized with allogeneic cells. Immune cell changes were analyzed by flow cytometry. Immunization resulted in significant leukocyte increases in all groups. B cells only varied for transplanted inbred mice. Outbred mice had significantly greater baseline T cells due to increased CD4+ T cells. CD8+ T cell numbers were comparable between the strains and groups. Interestingly, in outbred mice both CD4 and CD8 T cells responded equally while in inbred mice CD8 T cells were predominant. Outbred mice had peak responses later and more prolonged than inbred mice. Thus, inbred mice may not be an accurate model for testing immune responses in humans, especially after BMT.