Post-traumatic activation of draining lymph node cells. II. Proliferative and phenotypic characteristics.

Proliferative and phenotypic characteristics of cells in regional lymph nodes that drain burn injury were examined in rats on day 3 postburn, i.e. at the time of maximal spontaneous proliferation and of interleukin-2 and accessory cytokine (IL-1 and IL-6) production. The importance of IL-1 in spontaneous proliferation of draining lymph node cells was demonstrated by stimulation of IL-2-driven proliferation by recombinant IL-1 in vitro and by susceptibility of unstimulated proliferation to anti-IL-1 antibodies, while requirements for IL-6 in draining lymph node cell proliferation were less pronounced. Cell surface phenotyping revealed a slightly increased percentage of CD25+ cells in the blast cell population of freshly isolated draining lymph node cells after injury, which increased further during cultivation. Enrichment in CD8+ cells on day 3 following burn injury was demonstrated, while no changes in total cell population and CD4+ cells was noted. This was however preceded by pronounced percentual decrease of total T cells and CD4+ cells and by increases of B cells and MHC class II+ cells on day 1 postburn. Inhibition of draining lymph node cell proliferation by anti-MHC class II antibodies suggested that this proliferation was class II MHC dependent. The contribution of cell proliferation and/or cell influx to day 3 postburn draining lymph node cell activity is discussed.

Increased activity of lymph node cells in thermal injury.

While trauma-induced suppression of T-cell responses is well documented, only few studies address lymphocyte activation. The aim of this study was to investigate the functional activity of lymph node cells in rats subjected to scald injury, proliferative activity, cytokine production, and responsiveness to exogenously added cytokines was evaluated in cells from lymph nodes draining burned tissue and from distant, nondraining lymph node cells. Results presented clearly show that lymph node cells in scalded rats are activated in vivo although the extent of proliferation and pattern of cytokine production differ: a) proliferative activity was elevated both in draining and distant lymph nodes, but was more pronounced in cells from lymph nodes draining the injured region; b) increased production of IL-2, and particularly IL-1 and IL-6 was found and coincides well with peak of proliferative activity of draining lymph node cells; IL-2 production by distant lymph node cells remained unchanged, IL-1 and IL-6 production was significantly increased coinciding with increased proliferation; c) increased responsiveness to exogenously supplied cytokines was found in draining lymph node cells, while it remained unchanged in nondraining lymph node cells. Early activation of lymphocytes demonstrated in our experiments could be one of the previously unrecognized consequences of trauma-induced immunosuppression.