Qa antigen expression on functional lymphoid, myeloid, and stem cells in adult mice.

Abstract

Abstract The cellular representation and ontogeny of Qa antigen expression was studied with particular emphasis on B lymphocytes and myeloid cells. A polyvalent Qa antiserum was lytic in the presence of complement for almost all clonable B cells and a majority of granulocyte-macrophage progenitor cells and multipotential stem cells in adult B6 mice. Qa was demonstrated on B cells capable of primary immune responses to TNP-AECM-Ficoll, TNP-Brucella, and those mediating secondary IgE responses to DNP-Ascaris. These results imply that Qa is present on a number of functionally restricted B lymphocyte subsets. Strain distribution and absorption analyses and a comparison of different Qa antisera indicate that the predominant Qa antigen on cells other than T lymphocytes; is Qa-2. At least one antigen, presumably Qa-2, was shown by absorption to be common to T cells, B cells, myeloid progenitors, and stem cells. B cells of SWR/J strain mice were not consistently killed by anti-Qa serum although the presence of Qa on cells of these mice was demonstrable by absorption. This suggests that additional genes may modify the tissue distribution of Qa and/or the amount of antigen displayed. Appreciable amounts of Qa were not found on any of the cell types tested in newborn B6 mice and expression of Qa-2 was still increasing in the thymus and spleen of 4-week-old mice. These results indicate that Qa-2 is acquired by immature and mature members of several hemopoietic lineages at a very late stage of development.