Development of Immunodeficiency of Pituitary Dwarf Mice

Autosomal recessive pituitary dwarf mutants of the Snell-Baggand Ames mouse strains develop severe immunodeficiency of thethymus-dependent (T cell) system which frequently leads to afatal wasting syndrome. The ontogenetic development of the Tcell system is already subnormal soon after birth as evidencedby diminished responsiveness of thymus and spleen cells to phytohemagglutininand concanavalin A. The immunodeficiency of the dwarf mouseis a consequence of defective pituitary influences which willcause (i) an inadequate production of immunocompetent cellsdue to a central developmental defect primarily affecting thethymus, and (ii) the inability of immunocompetent cells to undergoa rapid and efficient antigen-induced proliferation and differentiationinto antibody-forming cells. The lack of epinephrine-inducedstimulation of adenylate cyclase activity in dwarf spleen andthymus cells suggests that the impaired lymphoid cell proliferationin dwarf mice may be due to inadequate stimulation of cyclicAMP production.