Deficiency in the thymus-dependent immunity in "lethargic" mutant mice.

T cell function of "lethargic" mutant mice which exhibit spontaneous thymic involution was evaluated by skin transplantation and graft-versus-host reaction tests. At 15 to 30 days of age, the mutant mice did not reject skin allografts, but by 45 days of age their response was normal. Spleen cells from 24-day-old mutant donors demonstrated delayed appearance of graft-versus-host induced splenomegaly in F1 recipients. Implications of these results in understanding the immunological status of lethargic mice were considered.