IGF-I alters lymphocyte survival and regeneration in thymus and spleen after dexamethasone treatment.
Insulin-like growth factor I (IGF-I) is a growth factor for the immune system, increasing lymphocyte number and function via greater lymphocyte generation and/or survival. We investigated the effects of IGF-I on lymphocyte survival and regeneration in the thymus and spleen after dexamethasone (Dex) treatment in rats maintained with parenteral nutrition and given recombinant human IGF-I (800 micrograms/day) for 12 h, 48 h, and 5 days. IGF-I did not prevent Dex-induced apoptosis of thymocytes but reduced cell death in the spleen at 12 and 48 h. IGF-I exerted a modest protective effect (10-15% reduction in cell loss) on all splenic T and B cell subsets examined by flow cytometry. IGF-I enhanced recovery of CD4+8+ immature T cells in the thymus and decreased the proportion of CD8+ (cytotoxic/suppressor) T cells in the spleen. In rats not treated with Dex, IGF-I significantly increased total lymphocyte number and the number of CD4+8+ T cells in thymus and spleen. Our results suggest that IGF-I may alter homeostasis in the immune system by modulating lymphocyte generation and survival.
Hinton
P S
PS
Department of Nutritional Sciences, University of Wisconsin-Madison 53706, USA.
Peterson
C A
CA
Dahly
E M
EM
Ney
D M
DM
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects; D002452:Cell Count / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010289:Parenteral Nutrition, Total; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000166:cytology / Q000187:drug effects*; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects*
D005938:Glucocorticoids; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone