FIG. 3.

CD4⁺ T cells from MZB cell-depleted mice have reduced responses to B. burgdorferi after in vitro stimulation. Splenocytes from 7-day-infected (A to C) and 14-day-infected (D) mice were stimulated with B. burgdorferi lysate for 72 h prior to immunofluorescent staining, as described in Materials and Methods. Gates were set on Thy1.2⁺ CD4⁺ cells. The activation marker expression on the gated cells from one representative mouse per group is shown in the histograms: light gray solid histogram, stimulated cells from an infected control mouse; black line, open histogram, stimulated cells from an infected MZB cell-depleted mouse; dark gray solid histogram, unstimulated cells from an infected control mouse; gray line, open histogram, unstimulated cells from an infected MZB cell-depleted mouse. The averages of the MFIs from the stimulated cells from five MZB cell-depleted mice were significantly different from those of five control mice (P = 0.02 [A], P = 0.01 [B], P = 0.003 [C], and P = 0.005 [D], as determined by a two-tailed Student's t test).