Lym 7.2: Monoclonal Antibody Defining an Alloantigen Similar or Identical to Ly 7.2

Abstract

Immunization of B10.D2 Igⁿ mice against a (BALB/c × NZB)F₁ murine B lymphoma cell line (WEHI-5) and subsequent fusion of immune spleen cells with a drug sensitive myeloma (P3×63-Ag8) has resulted in the generation of a series of hybridoma cell lines. One of these clones, BD5-334.5, secretes an antibody which reacts with a determinant, designated Lym 7.2, which demonstrates an identical tissue and strain distribution as the conventionally defined Ly 7.2 antigen. Furthermore, anti-Ly 7.2 alloantiserum significantly blocks reaction of the anti-Lym 7.2 monoclonal antibody with BALB/c splenocytes. Lym 7.2 is present on a majority of splenocytes, peripheral blood leukocytes, and lymph node cells. However, B cells express considerably higher cell surface density of this antigen than peripheral T lymphocytes. This antigen was not detected on erythrocytes, kidney, liver, or brain. Moreover, Lym 7.2 is present on approximately 15% of normal thymocytes, and 15% of bone marrow cells, and is expressed on cortisone resistant thymocytes. Quantitative flow cytometry analysis demonstrated that the antigen is present at approximately half the cell surface density on spleen cells from F₁ mice between Lym 7.2 positive and Lym 7.2 negative mice, but on the same percentage of cells as Lym 7.2 positive inbred strains. Data from backcross analysis suggest that a single locus is encoding this antigen. Mitogen blasts, induced with PHA, ConA, and LPS, all express the Lym 7.2 marker.