Gamma Globulin and Antibody Formation in Vitro I. Gamma Globulin Formation in Tissues from Immature and Normal Adult Rabbits*,

Studies on antibody formation "in vitro" have supplied information concerning the site of antibody production (1-5), the rates of antibody synthesis per unit weight of tissue (6-7) and the percentage of active cells in lymphoid tissue during the primary and secondary antibody response (8-9). In vitro experiments have also been used in attempts to elucidate the mechanism of induction of antibody formation by antigen (10, 11). Askonas et al. (12) studied the synthesis of gamma globulin by tissues from non-immunized and immunized rabbits. In their studies incorporation of labeled amino acid by rabbit tissue in vitro was shown to occur in protein which upon column chromatographic and electrophoretic fractionation behaved like gamma globulin. In tissues from immunized rabbits an enhanced synthesis of gamma globulin was shown to occur (13, 14). In the present study, the in vitro synthesis of gamma globulin was investigated using immunological techniques to isolate the gamma globulin rather than biochemical fractionation, because it was felt that such methods provide a better characterization of a protein, particularly in the presence of other tissue proteins. This method involves the measurement of the incorporation by tissue in vitro of labeled amino acid into a protein precipitable with an antiserum specifically directed against rabbit gamma globulin. With this method an attempt has been made to study further the relationship between gamma globulin and antibody formation in various tissues. The present paper presents evidence that, in immature rabbits, gamma globulin synthesis occurs predominantly in the lymphoid tissue of the intestinal wall. At this age rabbits show very low or negligible gamma globulin formation in spleen and thymus. The results on gamma globulin formation are correlated with the histological appearance of lymphoid organs of newborn and immature rabbits.