Agonistic CD40 stimulation induces GC-independent memory cell generation in the absence of T cells. (A) Combined data from three experiments showing the numbers of PE-specific GC, CD38⁺ GL7⁺ cells, IgM⁺ memory, and swIg⁺ memory cells in WT and Tcra^−/− mice with or without treatment with 250 µg anti-CD40 every other day beginning at the time of PE/CFA injection. The numbers of CD38⁺ GL7⁺ cells were calculated 6 d after injection, whereas the other populations were assessed at 9 d. To account for unstimulated naive cells contaminating the IgM⁺ memory population, the mean number of PE-specific cells found in uninjected animals was subtracted from the IgM⁺ population. Each data point represents an individual mouse and bars represent the mean. (B) Representative flow cytometry plots showing the expression of CD73 on PE-specific naive cells or swIg⁺ memory cells found in anti-CD40–treated Tcra^−/− mice 9 d after injection or WT mice 30 d after injection. Shown is a representative of three animals.