Analysis of lymphoid cell types developing in mouse foetal liver

Development of the immune system in human fetal liver

Fetal liver is a major site of development of the human immune system. Pre-B and B-lymphocytes are present in the human fetal liver at 12 weeks in a random distribution and increase with gestation. Most fetal liver cells are pre-B but mature B-cells are also present. Functional assays and transplantation experiments indicate that these B-cells are functional and can transfer immunologic memory, albeit imperfectly, in fetal liver reconstituted recipients. T-cell development, in contrast, occurs predominantly in the thymus. Progenitors of T-cells are present in fetal liver and can restore T-cell immunity in irradiated recipients. Human fetal liver contains 1-2% mature T-cells; functional assays are likewise negative. NK cells have been detected in human fetal liver at low frequency. Fetal liver also contains non-T, non-B cells capable of suppressing the development of alloantigen reactive T-cells; these have been termed veto cells. In summary, human fetal liver contains progenitors of several types of lymphoid cells and is an important site of immune development. It also may play a role in the induction of self tolerance during maturation of the immune system. These features of fetal liver may have important implications for the success of fetal liver transplantation in man.

Characterization of reactive and suppressive cells in the mouse embryonic liver by peanut agglutinin (PNA)

Embryonic liver cells suppressed the MLC response of adult mouse spleen cells and reactivity to mitogens Con A, PHA and LPS. Suppression was exerted by cells agglutinated by PNA (PNA+ cells). Cells reacting to LPS and to DxS were found in the nonagglutinated (PNA-) cell fraction. The PNA+ fraction did not react to DxS nor did it reduce the response of sdult spleen cells to this mitogen.

Immune reactivity during aging. I. T-helper dependent and independent antibody responses to different antigens, in vivo and in vitro

The immunological status during aging was assessed by measuring the antibody response of the long-lived (C3H/eb X C57Bl/6J)F1 mice to various antigens in vivo and in vitro. In vivo, a decrease in antibody production to DNP and NIP haptenic determinants coupled on to BGG, as well as the response to SRBC, was observed. The decline was more pronounced in the IgG as compared to IgM antibodies. The results were recorded when various parameters such as antigen dose and kinetics of the response, were considered. Reduction of the antibody response was also noted when PVP was employed as immunogen. Similar results were noted when the responses to SRBC and DNP--polylysine were induced and followed in spleen organ cultures. In all of these experimental systems, the peak response was observed in mice 6--12 months old. From then on a gradual decrease was manifested, mice 30--36 months old producing significantly low responses. The results demonstrate that decrease in antibody production is expressed in the isolated spleen tissue in the same manner as in the intact animal. Furthermore, they were interpreted as indicating that the lesion may be at the T helper and the B cell compartments.

Growth of mouse yolk sac cells cultured in vivo

The proliferation and differentiation of yolk sac cells from 10 1/2-day-old mouse embryos were studied in diffusion chambers implanted into syngeneic and allogeneic hosts. The most striking observation was the appearance, proliferation and predominance of immature and mature plasma cells. The data suggested that the differentiation into plasma cells and the rate of growth of yolk sac cells cultured in vivo may be dependent on the genetics of the strain of mouse and host. This demonstration of differentiation of plasma cells from yolk sac cells cultured in vivo adds further information to the origin and ontogeny of potentially immunocompetent cells.