Role of ovarian hormones in T-cell homeostasis: from the thymus to the periphery.
The study explored the putative role of ovarian hormones in the peripubertal remodelling of peripheral T-cell compartment. Ovariectomy at age of 1 month enhanced the peripubertal rise in CD4+ and CD8+ cell numbers in peripheral blood (PB) and spleen from 2-month-old rats. This reflected maintenance of thymopoietic efficiency at the prepubertal level (judging by numbers of the most mature CD4+ and CD8+ thymocytes and recent thymic emigrants) and alterations in T-cell survival/proliferation in the periphery. Compared with age-matched controls, the frequency of apoptotic cells among CD8+ peripheral blood lymphocytes (PBLs) and CD4+ and CD8+ splenocytes was diminished in ovariectomized (Ox) rats, at least partly, due to lower CD95 surface density. The diminished frequency of the apoptotic T splenocytes could also be associated with the rise in the amount of splenic IL-7 mRNA. Additionally, the latter finding was consistent with the augmented proliferation of CD4+ and CD8+ splenocytes. However, the enhanced proliferation of these cells could also be linked to the rise in IL-2 receptor surface density. This increase was related to the enhanced splenic TNF-α mRNA expression. Additionally, ovariectomy led to the phenotypic alterations in the major PBL and splenic T-cell subsets by diminishing/preventing the peripubertal changes in the frequency of cells at distinct stages of post-thymic differentiation/maturation (recent thymic emigrants, mature naïve and memory cells), and by decreasing the frequency of NKT cells within peripheral CD8+ subsets. In addition to numerical and phenotypic changes in T-cell compartment (due to the lack of ovarian hormone action at both the thymic and peripheral level), Ox rats exhibited a much larger delayed-type hypersensitivity (DTH) response compared with age-matched controls. This suggested the augmented T-cell-mediated immune response in Ox rats compared with aged-matched controls.
Immunology Research Centre Branislav Janković, Institute of Virology, Vaccines and Sera Torlak, Belgrade, Serbia.
Milica
M
Perišić
Zorica
Z
Stojić-Vukanić
Ivan
I
Pilipović
Duško
D
Kosec
Mirjana
M
Nacka-Aleksić
Jasmina
J
Dikić
Nevena
N
Arsenović-Ranin
Gordana
G
Leposavić
D000818:Animals; D001775:Blood Circulation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D005260:Female; D006706:Homeostasis; D006728:Hormones / Q000378:metabolism; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D055611:Natural Killer T-Cells / Q000276:immunology*; D010052:Ovariectomy; D010053:Ovary / Q000276:immunology*; D011627:Puberty; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D006728:Hormones; D014409:Tumor Necrosis Factor-alpha