Alterations during positive selection in the thymus of nackt CD4-deficient mice.
The T-cell repertoire is shaped by the positive and negative selection of immature CD4(+) CD8(+) double positive (DP) thymocytes. Positive selection of DP T cells to the CD4(+) CD8(-) and CD4(-) CD8(+) simple positive (SP) lineages is a multistep process which involves cellular interactions between thymocytes and stromal cells. Mutant nackt (nkt/nkt) mice have been shown to have a deficiency in the CD4(+) CD8(-) T-cell subset both in the thymus and in the periphery. The present report suggests that nkt/nkt mice present alterations in early steps of positive selection because they show decreases in the percentages of CD69(+) and CD5(+) cells within the DP subset. Experiments involving bone marrow transfer and thymic chimeras demonstrate that the thymic epithelium of nkt/nkt mice is involved in the alterations registered during positive selection and dictates the ultimate fate of CD4(+) SP cells.
Nepomnaschy
I
I
ILEX-CONICET, División Medicina Experimental, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina. irenepo@sinectis.com.ar
Lombardi
G
G
Bekinschtein
P
P
Berguer
P
P
Francisco
V
V
de Almeida
J
J
Buggiano
V
V
Pasqualini
C D
CD
Piazzon
I
I
D000505:Alopecia / Q000235:genetics; D000818:Animals; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D018956:CD5 Antigens; D016827:CD8 Antigens; D007111:Immunity, Cellular / Q000276:immunology; D037181:Lectins, C-Type; D051379:Mice; D008817:Mice, Mutant Strains / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D018956:CD5 Antigens; D016827:CD8 Antigens; D037181:Lectins, C-Type; D000099192:CD69 Antigens