We evaluated MAPK (Erk 1/2 and p38) signaling mechanisms of altered T-cell-mediated immune responses in thermal injury condition. Rats were subjected to 30% body surface scald burn, and their mesenteric lymph node (MLN) and Peyer's patch (PP) T cells were purified using nylon wool method. Activation of MAPKs, Erk 1/2 and p38 was assessed in T cells by determining its phosphorylation using immunoblot analysis, intracellular immunostaining and confocal microscopy. The results showed a down-regulation of Erk 1/2 and p38 activation in anti-CD3-stimulated T cells from thermally injured animals, compared to Erk 1/2 and p38 in sham rat T cells. The down-regulation of MAPKs in T cells was reversed by treatment of T cells with calcium agonist, ionomycin. These data indicate that attenuated MAPKs (Erk 1/2, p38) activation in thermally injured animals' T cells could result from derangement of Ca(2+) mobilization. This finding suggests that T cell signaling derangements with thermal injury involve an altered cross-talk between Ca(2+) mobilization and MAPK signaling mechanisms.