Altered thymic structure and mitogen responsiveness in postnatally zinc-deprived mice

The influence of postnatal zinc deprivation on the development of thymic strucutre and splenic mitogen responsiveness was investigated by feeding dams of suckling mice, during the first four weeks post-partum diets containing various levels of zinc (9.0 p.p.m. zinc, or marginal deficiency; 5.0 p.p.m. zinc, or moderate deficiency; 2.5 p.p.m. zinc, or severe deficiency; 100 p.p.m. zinc, fed either ad libitum, or isocaloric with the level of inanition observed in moderately deprived mice). Mice deprived of zinc manifested a dramatic retardation of splenic, and most notably, thymic growth and development, far in excess of the degree of stunting observed in the whole animal. Indeed, severely deprived animals possessed only a thymic rudiment. Moderately and severely deprived offspring demonstrated marked depression of splenic responsiveness to the mitogens, Con A, PHA-P, Pokeweed and E. coli lipopolysaccharide. Nonetheless, while response to the mitogens Pokeweed and lipopolysaccharide was depressed, response to the T-cell mitogens Con A and PHA-P was most severely altered. Pups deprived of zinc had only 5-10% of the stimulation index to Con A and PHA-P of ad libitum-fed and food-restricted control animals. The near total elimination of response to mitogens of thymus-derived lymphocytes correlated with the severely hypoplastic thymuses seen in zinc deprived progeny.