FIGURE 5.

T cells contribute to Ab production following i.n. exposure and protection against subsequent i.t. challenge. (A) Three weeks after NP exposure of 8- to 10-wk-old wild-type or TCRβxδ^–/– mice with S. pneumoniae TIGR4, IgG (top) and IgA (bottom) Abs against indicated Ags were titered in the sera of wild-type (○) or T cell–deficient (▴) mice. Ab units were calculated based on a hyperimmune standard included in each ELISA plate, and the background titers, determined by ELISA of serum of naive mice, were subtracted from the data (see Materials and Methods). The indicated p values were determined using a Student t test. Asterisks represent statistical significance (p < 0.05). Dotted lines represent limit of detection. (B) Three weeks after NP exposure, wild-type and T cell–deficient mice (TCRβxδ ^–/– ) were challenged i.t. with 2 × 10⁶ CFU of S. pneumoniae TIGR4. Survival was assessed at the indicated time points after challenge. Fractions denote survivors 2 wk after challenge over the total number of mice, and asterisks indicate statistical significance (p < 0.05) by the log-rank (Mantel–Cox) test. n.s., not significant.