Figure 4.

Purified LTα-expressing and LTα-deficient T cells both restore GC formation in TCR^−/− mice. Unirradiated TCR^−/− mice were treated with an infusion of 10⁷ purified T cells from the spleens of LTα^−/− (B, D, and F) or wild-type mice (A, C, and E). At the same time, the mice were immunized with 10⁸ SRBCs administered intravenously. The spleens of the recipients were harvested 10 d later, and frozen sections were stained as described for Fig. 2. A and B are stained for B (brown) and T (blue) cells; C and D are stained for B cells (brown) and FDC (blue); E and F are stained with B220 (brown) and PNA (blue).