STRESSFUL STIMULATION OF NEWBORN MICE INCREASES THE IN-VITRO PROLIFERATIVE RESPONSE IN T-CELLS FROM THYMUS

The effects of prolonged stressful stimulation on the in vitro prolife rative response of thymic T cells and the thymic zinc concentration we re investigated in newborn Balb/c mice. Animals were stressed by intra peritoneal injections with aliquots from a heat-killed staphyloccocal suspension over one month. The splenic T lymphocytes from the stressed animals showed a significant reduction in the in vitro response to Co ncanavalin A (Con-A) stimulation. However, an unexpected and significa nt increase in proliferative response was observed when thymic lymphoc ytes from stressed animals were stimulated with the same mitogen. The intrathymic zinc levels were regularly elevated in stressed mice, in c ontrast to those values obtained in the thymus from healthy control mi ce. These results suggest that neonatal stress can disrupt the intrath ymic maturation and the selection of pre-T lymphocytes. The increment of the in vitro proliferative response of T cells from the thymus of s tressed mice may be caused by proportionally higher amounts of intrath ymic lymphoid subpopulations expressing a mature phenotype and functio nality.