T-lymphocyte Ca2+ signalling and proliferative responses during sepsis.

Alterations in T-lymphocyte kinetics and/or activation have been implicated in burn and traumatic injury. This study evaluated concanavalin A (Con A) regulation of both intracellular Ca2+ (Ca2+i) and proliferation in T-lymphocytes harvested from spleens of septic rats. Rats were implanted with fecal pellets containing Escherichia coli (150 colony forming units (CFU)) and Bacteroides fragilis (10(4) CFU). T-cell [Ca2+]i was measured before and after treatment of cells with Con A, using Fura-2 and microfluorophotometry. Splenic lymphocytes were cultured for 72 h with Con A to assess their proliferative response. As compared to sterile-implanted rats, the septic rat T-lymphocytes Ca2+i response to ConA significantly decreased on days 1 and 2 after implantation. A significant decrease in T-cell proliferative response to Con A, compared to sterile controls, was found in septic rats on day 2 but not on day 1. These results suggest that Con A-mediated proliferation in T-cells occurs secondarily to a decrease in cellular Ca2+ signalling. The depression in the T-cell proliferative response during sepsis could contribute to a decrease in host's resistance against sepsis.