Beta-1C and immune globulin formation in vitro by tissues from germ-free and conventional rodents of various ages.

synthesis of β and immune globulins by tissues from foetal, neonatal and adult guinea-pigs, rabbits, mice and rats, was studied using a combination of immunoelectrophoresis and autoradiography. Germ-free (GF) mice and rats of various ages were also included in an effort to evaluate maturation of serum protein formation in an environment free of living bacteria. In all these species IgM is the first immune globulin detected, and its production is most prominent in the spleen. Formation of IgM is correlated with the degree of maturity at birth which in turn is dependent upon the length of the gestation period. In guinea-pigs, and probably also in mice, early IgM synthesis is accompanied by the production of free L chains. In the guinea-pig IgM synthesis is followed by formation of IgG. Production of IgG was first noted at 3–4 weeks of age. In GF animals IgM production by the spleen developed at the same time and to approximately the same degree as in conventional (CVL) animals. Under CVL conditions mesenteric lymph nodes of immature animals developed early and strong synthesis of IgG. In contrast, mesenteric lymph nodes from GF animals remained markedly inactive. Although β was produced by all lymphoid tissue, there was no correlation with immune globulin formation, and the influence of age was evident only in the liver. Liver synthesis of β was low during foetal or neonatal life, depending on the degree of maturity at birth, increased in young animals, and then decreased again in adulthood.