Burn injury-mediated alterations in cell cycle progression in lymphoid organs of mice.

A key event in the cellular and molecular pathogenesis of multiple organ failure (MOF) after burn injury may be the change in profiles of the cell cycle progression in affected organs. We investigated the effects of burn injury on cell cycle progression in immune organs. Cell cycle analysis in the lymphoid tissues of mice after 18% burn injury revealed that S phase entry was temporarily arrested in the thymus 1 day after injury, whereas the spleen had substantially increased S phase entry at day 8. This mode of cell cycle regulation was reproduced in different age groups and strains of mice. Furthermore, the reactivity to the Ki-67 antibody (indicative of proliferation) was markedly reduced in the thymic cortex at day 1. There was a distinct pattern of hematopoietic foci formation and increased reactivities to the Ki-67 antibody in myelogenous cells in the red pulp of spleen at day 7, consistent with the elevated S phase entry. These data suggest that differential regulation of cell cycle progression may play a crucial role in the phenotypic changes in immune organs after burn injury.