Functional Development of the Interacting Cells in the Immune Response

Abstract

Abstract The functional ontogeny of the interacting T cell and B cell4 populations in the antibody response to sheep erythrocytes (SRBC) was investigated in CBA mice. It was found that T cell function, as determined by the ability of test cells to interact with adult bone marrow cells, was not detectable in fetal or neonate liver or lung. Moreover, even in the thymus this function remained less than 10% of adult values until birth. At birth T cell function increased exponentially, reaching adult levels within 48 hr. Neonatally thymectomized mice reconstituted with thymus cells of various ages confirmed these results. By day 4 after birth, T cell function could be detected in the spleen. B cell function, as determined by the ability of test cells to interact with adult thymus cells, was detected in the neonate spleen from day one. Therefore, both B cell and T cell function was present in the spleen from day 4 after birth. B cell function also was found in the fetal and neonate liver. B cell function of fetal liver was only 1/6 that of adult bone marrow on fetal day 16, quickly surpassed adult bone marrow activity near birth, and then equalled adult bone marrow activity until day 6 after birth. The ontogeny of B cell and T cell function in the antibody response to SRBC appears to take place at separate times in the mouse. B cell function develops first, most probably from the most primitive stem cell. T cell function develops later, after a structural thymus is present. Migration of T cell lymphocytes to other lymphoid tissue shortly after birth is consistent with the data presented.