H9/25 monoclonal antibody recognizes a new allospecificity of mouse lymphocyte subpopulations: Strain and tissue distribution

C3H/He‐mg mice were immunized with C57 BL/10 (B10) spleen cells and the immune spleen cells were fused with BALB/c myeloma cells (NS1). One of the monoclonal antibodies (H9/25 antibody) produced by the hybrid cells was studied. It reacts with subpopulations of B 10 lymphocytes as well as some lymphoid tumor lines including some of the Abelson virus‐induced leukemias. The antigen recognized by H 9/25 antibody is expressed on lymphocytes from all the B 10 congeneic mice tested as well as some other strains of mice. No linkage between genes coding for the antigen and H‐2 loci was found as judged by its presence on cells of the B 10 strains regardless of H‐2 type and the distribution of the antigen on Bailey recombinant inbred mice. The antigen is expressed on subpopulations of lymph node cells, spleen cells, thymocytes and bone marrow cells. The strain distribution of the H9/25 antigen seems to be identical to that of Ly‐6, Ly‐8 and Ala‐1 antigens. However, the tissue distribution of the antigen recognized by H9/25 antibody, while similar to these alloantigens, is unique and the antigen may be distinct from the other alloantigens.