FIG. 5.

Cytokine assay with LN at 12 weeks postinfection. CD4⁺ LN cells were restimulated with SLA for 48 h. Subsequently, the IFN-γ and IL-4 contents in the supernatants were determined. CD4⁺ LN cells from young BALB/c mice that were restimulated with SLA regularly showed a cytokine pattern typical for a Th2 response. In contrast, CD4⁺ LN cells from infected senescent BALB/c mice showed a significant increase in the L. major-specific release of IFN-γ (A). Their release of IL-4 was not significantly lower than that from T cells of young infected mice (178 ± 114 pg/ml in senescent mice versus 289 ± 51 pg/ml in young mice). However, when only mice with healed ulcerations were considered for comparison (n = 3), their release of IL-4 was significantly lower than that from young mice (B). (A) Data are means and SD (n = 5) for all mice; (B) data are means and SD (n = 3) for mice with healed ulcerations. *, P < 0.05 for differences between young and aged mice. Dashed line, no stimulation.