Alterations during positive selection in the thymus of nackt CD4-deficient mice

NEPOMNASCHY, IRENE; LOMBARDI, GABRIELA; BEKINSCHTEIN, PEDRO; BERGUER, PAULA; FRANCISCO, MARÍA VIRGINIA; DE ALMEIDA, JULIÁN; BUGGIANO, VALERIA; DOSNE DE PASQUALINI, CHRISTIANE; PIAZZON, ISABEL; MARGARITA ISABEL PIAZZON

SCANDINAVIAN JOURNAL OF IMMUNOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: OXFORD; Año: 2000 vol. 52 p. 555 - 562

0300-9475

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.