Heterogeneity of NK1.1(+) T cells in the bone marrow: Divergence from the thymus

NK1.1(+) T cells in the mouse thymus and bone marrow were compared because some marrow NK1.1(+) T cells have been reported to be extrathymically deriv ed. Almost all NK1.1(+) T cells in the thymus were depleted in the CD1(-/-) , beta(2)m(-/-), and J(alpha)281(-/-) mice as compared with wild-type mice. CD8(+)NK1/1(+). T cells were not clearly detected, even in the wild-type m ice. In bone marrow from the wild-type mice, CD8(+)NK1.1(+) T cells were ea sily detected, about twice as numerous as CD4(+)NK1.1(+) T cells, and were similar in number to CD4(-)CD8(-)NK1.1(+) T cells. All three marrow NK1.1() T cell subsets were reduced about 4-fold in CD1(-/-) mice. No reduction w as observed in CD8(+)NK1.1(+) T cells in the bone marrow of J(alpha)281(-/- ) mice, but marrow CD8(+)NK1.1(+) T cells were markedly depleted in beta(2) m(-/-) mice. All NK1.1(+) T cell subsets in the marrow of wild-type mice pr oduced high levels of IFN-gamma, IL-4, and IL-10. Although the numbers of m arrow CD4(-)CD8(-)NK1.1(+) T cells in beta(2)m(-/-) and J(alpha)281(-/-) mi ce were similar to those in wild-type mice, these cells had a Th1-like patt ern (high IFN-gamma and low IL-4 and IL-10). In conclusion, the large major ity of NK1.1(+) T cells in the bone marrow are CD1 dependent. Marrow NK1.1( +) T cells include CD8(+), V(alpha)14-J(alpha)281-, and beta(2)m-independen t subsets that are not clearly detected in the thymus.