Dysregulation of T-cell development in adrenal glucocorticoid-deprived rats.
A number of different experimental approaches have been used to elucidate the impact of basal levels of adrenal gland-derived glucocorticoids (GCs) on T cell development, and thereby T cell-mediated immune responses. However, the relevance of the adrenal GCs to T cell development is still far from clear. This study was undertaken to explore the relevance of basal levels of GCs to T cell differentiation/maturation. Eight days post-adrenalectomy in adult male rats the thymocyte yield, apoptotic and proliferative rate and the relationship amongst major thymocyte subsets, as defined by TCRalphabeta/CD4/CD8 expression, were examined using flow cytometry. Adrenal GC deprivation decreased thymocyte apoptosis and altered the kinetics of T cell differentiation/maturation. In the adrenalectomized rats there was increased thymic hypercellularity and an over-representation of the CD4+CD8+ double positive (DP) TCRalphabeta(low) cells entering selection, as well as increased numbers of their DP TCRalphabeta(-) immediate precursors. These changes were accompanied with under-representation of the postselected DP TCRalphabeta(high) and the most mature CD4-CD8+ and, particularly, CD4+CD8- single positive (SP) TCRalphabeta(high) cells. This data suggests that withdrawal of adrenal GCs produces alterations in the thymocyte selection processes, possibly affecting the diversity of functional T cell repertoire and generation of potentially self-reactive cells as indicated by the reduced proportion and number of CD4-CD8- double negative TCRalphabeta(high) cells. In addition, it indicates that GCs influence the post-selection maturation of thymocytes and plays a regulatory role in controlling the ratio of mature CD4+CD8-/CD4-CD8+ SP TCRalphabeta(high) cells.
Stojić-Vukanić
Zorica
Z
Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, 11221 Belgrade, Serbia.
Rauski
Aleksandra
A
Kosec
Dusko
D
Radojević
Katarina
K
Pilipović
Ivan
I
Leposavić
Gordana
G
D000311:Adrenal Glands / Q000502:physiology*; D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects*; D005434:Flow Cytometry / Q000379:methods; D005938:Glucocorticoids / Q000494:pharmacology*; D007155:Immunologic Factors / Q000494:pharmacology*; D008297:Male; D051381:Rats; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology*
D015704:CD4 Antigens; D016827:CD8 Antigens; D005938:Glucocorticoids; D007155:Immunologic Factors; D016693:Receptors, Antigen, T-Cell, alpha-beta