Maturation of mitogenic response in foetal guinea-pig.

Lymphocytes obtained from thymus, spleen and heart blood of 33-day-old guinea-pig foetuses and from lymph nodes of 48-day-old foetuses onwards were stimulated by phytohaemagglutinin (PHA). concanavalin A (Con A) and dextran sulphate (DxS). The results, based on the analysis of ninety-five foetuses, indicated that the mitogenic responses of the guinea-pig T cells matured first in the thymus and then in the spleen and lymph nodes, in that order. The PHA and Con A responses in the thymus, spleen and lymph nodes and the DxS response in the spleen improved with the increasing age of the foetus. A clear improvement of the mitogenic responses did not take place in the blood. Thus, at birth the guinea-pig is immunologically mature as regards the PHA and Con A responses in the thymus, spleen and lymph nodes and the DxS response in the spleen. Regarding the maturation of PHA and Con A responses by lymphocytes from the blood, further studies are needed, since at birth both of these responses are clearly below the adult level.