Relationship of Germinal Centers in Lymphoid Tissue to Immunologic Memory

Abstract

Summary Cell suspensions, obtained from white and red pulp of rabbit spleens at various days after priming, were examined for their ability to respond, with increased proliferation, to reexposure to antigen. A comparison was made between the proliferative response and the secondary in vitro antibody response obtained with the same tissues. A significant increase in mitotic activity in response to antigen was seen in white pulp as early as day 3 after priming. The maximum response was obtained on days 7 to 10. Neither of the antigens elicited a significant proliferative response in red pulp cells. However, in view of an unusually high background activity found in many of the red pulp suspensions, a limited stimulatory effect of antigen may have gone undetected. A fairly good correlation was found between the proliferative and secondary antibody response of white and red pulp and a relationship to the development of germinal centers in the white pulp was suggested. The first striking responsiveness occurred at the time when germinal centers are beginning to form, and maximum responsiveness was noted at the time of their peak development.