Tissue localization of complement component 3 receptor-bearing cells in lymphoid tissue after injection with complete Freund adjuvant.

Localizations of complement component 3 (C3) receptor (C3R)-bearing cells in lymph nodes obtained from normal guinea pigs or from guinea pigs inoculated with complete Freund adjuvant were examined by staining with fluorescein-labeled anti-guinea pig C3 antibody after treatment with aggregated rabbit immunoglobulin M bound with guinea pig complement. In normal lymph nodes, a small number of C3R-positive cells were observed in the cortical and medullary areas. Non-granulomatous lymph nodes from complete Freund adjuvant-inoculated animals showed a number of C3R-positive lymphocytes in a mantle zone of the secondary follicles between the follicles and medullary cords, whereas in the paracortical areas and germinal centers, only a few positive cells were scattered. Long-lasting existence of positive cells was seen in the epithelioid cell granuloma, although the staining patterns were different from those of the lymphocytes. The appearance of a number of C3R-bearing lymphocytes in lymph nodes from complete Freund adjuvant-inoculated animals might be an expression of adjuvant activity.