Differentiation of Forbidden T Cell Clones and Granulocytes in the Parenchymal Space of the Liver in Mice Treated with Estrogen

Estrogen was administered to B6 (NK1.1+strain), BALB/c (Mls-1b2a, Vβ3+cells being forbidden clone), or (B6 × BALB/c) F1mice (1 mg/mouse). On days 3 and 10, the number of cells yielded by the liver doubled, whereas that yielded by the thymus decreased prominently. The numbers of cells in the spleen, bone marrow, and blood were unchanged. c-kit+stem cells, which give rise to multilineage cells, were present in the liver and bone marrow. The proportion of such c-kit+cells in the liver increased while that in the bone marrow decreased on day 3. Therefore, the absolute number of c-kit+stem cells increased severalfold in the liver and clusters of lymphoid cells became visible in the parenchymal space. At that time, the expression of recombination activating gene-1 and -2 mRNAs became prominent. Reflecting these phenomena, the number and proportion of IL-2Rβ+CD3intcells (i.e., primordial T cells) increased in the liver on days 3 and 10. An increase in the number or proportion of such CD3intcells was seen even in the thymus and uterus. In parallel with the increase of CD3intcells, the proportion of granulocytes also increased in various organs on day 3. Forbidden clones were present in either the NK1.1+or the NK1.1−subset of CD3intcells in (B6 × BALB/c) F1mice treated with estrogen and liver mononuclear cells in such mice acquired potent cytotoxicity against syngeneic thymocytes. These results reveal that estrogen has the ability to potentiate the generation of self-reactive T cells and granulocytes in the liver and other organs.