RESUMEN
Germinal center (GC) is a critical site where the humoral immune responses take place. Especially memory cells are known to be generated from the GC. In this experiment, T cells observed in the GC were studied in the aspect of memory T cells. T cells responding to myelin basic protein (MBP) antigen usually have their own specific T cell receptor complex (TCR) consisting of V 2 and V 8. Therefore, MBP antigen enables to trace specific T cells reacting to MBP antigen. This experiment, in which balb/c mice were injected with MBP into footpad and the popliteal lymph nodes were removed, showed that most of V 2 +/- cells were L3T4 +/- cells, and that initially they were located in the deep cortex near the B cell follicles and later they were observed in the GC. In case of the primary injection of MBP, IL -4 +/- cells were observed for the first time, followed by appearance of CD69 and CD2R. In case of the secondary injection, all of IL -4, CD25, CD69, CD2R and CTLA -4 were observed from the 1st day after injection. However IL -4, CD25 and CD69 among them were not observed any more since 2 wks after the secondary injection. These results strongly suggest that T cells observed in the GC during the immune responses for MBP might be memory T helper cells.