title: Human germinal center T cells are unique Th cells with high propensity for apoptosis induction.
abstract: Collaborative interactions between T(h) cells and B cells are necessary for the production of antibody responses to most protein antigens and for the generation of memory B cells in germinal centers (GCs). Although it is well established that T(h) cells are pivotal for the GC reaction, the mechanisms that control the homeostasis of T(h) cells during the GC response remain largely unknown. Here we show that, unlike other effector T cells, a significant number of CD4(+)CD45RO(+)CD57(+) T cells, which are the major T(h) cells residing in the GCs, are undergoing apoptosis in vivo. CD4(+)CD45RO(+)CD57(+) GC T cells exhibit similar sensitivities to apoptotic signals and to caspase inhibitors as immature thymocytes. Moreover, CD4(+)CD45RO(+)CD57(+) GC T cells express a unique profile of genes that control apoptosis and cell cycle, providing possible molecular mechanisms for the high rates of apoptotic death of these T(h) cells in the GCs.
authors.affiliation: Department of Immunology, Baylor College of Medicine, M929, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Marinova
authors.forename: Shuhua
authors.initials: S
authors.lastname: Han
authors.forename: Biao
authors.initials: B
authors.lastname: Zheng
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D018959:CD57 Antigens / Q000276:immunology; D020169:Caspases / Q000378:metabolism; D018858:Germinal Center / Q000276:immunology*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology; D019014:fas Receptor / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D018959:CD57 Antigens; D011948:Receptors, Antigen, T-Cell; D019014:fas Receptor; D017493:Leukocyte Common Antigens; D020169:Caspases