Fetal Liver: A Source of Immunoglobulin Producing Cells in the Mouse.

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Abstract
Adult-thymectomized and intact (C57L x A)F1 mice were X-irradiated (870) rad), and injected ip with 20-33 x 106 nucleated cells from livers of 14-21 day C57bl/6 x C57B1/6 embryos. In other experiments the mice received 0. 3 x 106 syngeneic bone marrow cells (iv), and dissociated gut cells from 14-21 day C57B1/6 x C57B1/6 embryos (ip). The sera from these chimeras were assayed for the presence of donor-type [gamma] -globulins. These mice were also sensitized to a synthetic polypeptide (TGAL), and their sera tested for total and for donor-type anti-TGAL antibody. All the mice, thymectomized as well as intact, which received fetal liver cells, had significant quantities of donor-type [gamma]-globulins in their sera by 58 days postirradiation. Only 1 of 14 mice injected with embryonic gut cells was found to have donor-type [gamma]-globulins by 95 days postirradiation. Following immunization with TGAL, the fetal liver cell chimeras (intact thymus) exhibited specific antibody (10/10), while none of the thymectomized chimeras (0/21) were positive for this antibody. In the immunized, intact-thymus group, from 10 percent to 75 percent of the specific anti-TGAL antibody was of donor origin. Thus, mouse fetal liver, as early as the 14th day of gestation, contains lymphoid stem cells capable of immunoglobulin synthesis in the absence of thymus. However, their ability to form certain specific antibodies is dependent upon intact thymic function. The results suggest that the donor-type immunoglobulins synthesized in the absence of the thymus may be ''nonsense'' or ''defective'' antibody-like molecules .