FIG. 4.

Proliferative responses of CD4⁺ Th cells from infected BL/6, CBA, and BALB/c mice to rSm-PEPCK. CD4⁺ Th cells were isolated from mesenteric lymph nodes of 8.5-week-infected mice and incubated with the indicated antigens in the presence of APC as described in Materials and Methods. [³H]dThd incorporation was assessed by liquid scintillation spectroscopy. Data are expressed as mean counts per minute (error bars, 1 standard deviation). Background counts per minute from cells cultured in the absence of antigen were subtracted. Also shown for comparison are the responses to rSm-p40 and SEA. This experiment was repeated three times for BL/6 and CBA and twice for BALB/c, with similar results.