Enhancement of primary systemic acquired immunity by exogenous triiodothyronine in wasted, protein-energy malnourished weanling mice.

The objectives of this investigation were to expand information regarding the types of acquired immune responses that can be stimulated by triiodothyronine (T3) supplements in wasting protein-energy malnutrition (PEM) and to determine whether T3 can exert its enhancing influence on acquired immunity in PEM against diverse genetic backgrounds. Two experiments were conducted with weanling C57BL/6J mice. Animals were allowed ad libitum access for 14 d to a nutritionally complete purified diet (C), an isoenergetic low protein (0.6%) formulation (LP) or the low protein diet containing 0.2 microgram T3/g (LPT3). The LP diet produced wasting as judged by weight loss and carcass composition. This diet also depressed both the antibody response to sheep red blood cells (Experiment 1) and the complete major histocompatibility complex-disparate skin graft rejection response (Experiment 2). The LPT3-fed mice experienced wasting at least equivalent in magnitude to that of animals fed LP, but they exhibited significantly more vigorous responses than LP-fed animals in both immune reactions examined. In conjunction with previous results obtained using the CBA/J strain of mouse, the results show that not only humoral (antibody) responses but also at least some cell-mediated responses can be improved by T3 supplements in wasting PEM. Moreover, this influence on acquired immunity is apparent in at least two genetically unrelated mouse strains, thus increasing confidence in its basic biological significance.