ROLE OF GERMINAL CENTER IN IMMUNE RESPONSE ENZYME IMMUNO‐HISTOCHEMICAL STUDY USING HORSERADISH PEROXIDASE

Using enzyme Immuno‐hlstochemlcal method with horseradish peroxidase (HRP), a study on the relation between localization of antigen and antibody, and development of germinal center in lymph node after primary and secondary stimulation was made. Blastic antibody forming cells and intercellular localization of the antibody were noticed in newly formed germinal centers of draining lymph nodes within 7 days after primary antigenic stimulation. With increase of circulating antibodies produced by the draining lymph nodes, it accumulated in ready made germinal centers of generalized non‐draining lymph nodes. At the time of primary stimulation, the HRP antigen was never observed in solid follicles or newly formed germinal centers, and even in ready made germinal centers it became localized only transiently and was never retained. After secondary stimulation, the antigen accumulated quickly in the light zone of germinal centers, being trapped by the previously present antibody. Three days later, antibody forming cells began to be noticed in germinal centers as well as in medullae of non‐draining lymph nodes where no antibody forming cells had been so far observed, and in medullae of draining lymph nodes they increased markedly. Passively injected anti‐HRP antibody accumulated also in germinal centers of non‐primed mice and successively injected antigen was easily trapped in these germinal centers. Passively injected soluble antigen‐antibody‐complexes were localized in germinal centers of non‐primed mice. In both these cases, antibody forming cells appeared only in germinal centers and none in medullae. Blastic cells, proliferating in germinal center and producing 2‐ME sensitive antibody were not considered to be directly related with antibody forming cells in the medulla of lymph node.