Glucocorticoid and Fas ligand induced mucosal lymphocyte apoptosis after burn injury

Background: The purpose of this study was to examine the effects of a steam burn injury on apoptosis in gut-associated lymphoid tissue and to determin e whether endogenous glucocorticoid and Fas ligand signaling were involved in this process. Methods: Histologic analysis, in situ deoxynucleotidyl transferase dUTP nic k-end labeling staining and annexin V and 7-amino-actinomycin-D flow cytome try of lymphocyte populations were evaluated in intraepithelial lymphocytes and Peyer's patch. Additional mice were pretreated with a glucocorticoid r eceptor antagonist (mifepristone) before the steam burn. Similarly, C3H/HeJ -FasL(gld) mice lacking functional Fas ligand were also studied. Results:Apoptosis was significantly increased in intraepithelial lymphocyte s and Peyer's patch after the burn injury. Mifepristone pretreatment signif icantly reduced apoptosis in both T- and B-cell populations in intraepithel ial lymphocytes after the burn injury. In contrast, the increased apoptosis seen in B-cells from Peyer's patch was not seen in C3H/HeJ-FasL(gld) mice, whereas the increased apoptosis in CD8(+) T-cells was unaffected. Conclusion: Both corticosteroids and FasL contribute to the apoptosis in gu t-associated lymphoid tissues early after burn injury.