Unusual T cell populations in adult murine bone marrow. Prevalence of CD3+CD4-CD8- and alpha beta TCR+NK1.1+ cells.
The T cell populations present in normal murine bone marrow have not been previously analyzed in detail, mainly because of their relative rarity. In order to permit such analyses, bone marrow T cells were enriched by depleting Mac1-positive cells, which constitute 65 to 90% of bone marrow cells (BMC), and then studied by two-color flow cytometry. Analysis of the remaining cells revealed that the T cell profile of adult murine bone marrow is markedly different from that of other lymphoid organs. A very high proportion of bone marrow CD3+ cells (approximately one-third) are CD4-CD8-. CD3+CD4-CD8- cells are much more concentrated among BMC T cells than among thymocytes or splenic T cells, suggesting that bone marrow may be either a site of extrathymic TCR gene rearrangement, or a major site to which such cells home from the thymus. The expression of NK1.1 was also evaluated on Mac1-depleted BMC populations. Surprisingly, up to 39% of alpha beta TCR+ BMC were found to express NK1.1. Most alpha beta TCR+NK1.1+ BMC also expressed CD4 or CD8. NK1.1+ alpha beta TCR+ cells represented a much greater proportion of BMC T cells than of other lymphoid (splenocyte or thymocyte) T cell populations. Mac1-depleted BMC of nude mice contained very few cells with this phenotype. These results are consistent with the hypothesis that NK1.1+ alpha beta TCR+ cells are generated primarily in the thymus of normal animals and migrate preferentially to bone marrow, where they may function as regulatory elements in hematopoiesis.
Sykes
M
M
Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
D000818:Animals; D015703:Antigens, CD / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D001853:Bone Marrow / Q000276:immunology*; D017252:CD3 Complex; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens; D006410:Hematopoiesis; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D018800:Thy-1 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018800:Thy-1 Antigens