Monoclonal antibodies to routine lymphocyte cell membrane alloantigenic determinants (CMAD) have proven valuable as tools for serological, genetic, and functional studies. An expansion of the library of murine CMAD would be facilitated by an increase in the repertoire of antibodies. We report here a lymphocyte CMAD, designated Ly-27.2, that is common to both T-cell and B-cell lineages, but which was not found on bone marrow cells. Although Ly-27.2 has been reported previously (Hogarth et al. 1984), that specificity is now designated Ly-6D.2 (H. C. Morse, personal communication).
The monoclonal antibody defining the Ly-27.2 specificity was produced from BALB.B mice immunized intraperitoneally three times over a period of two months with 2 x 107 C57BL/10J lymphoid cells. Two days after a final intravenous injection, the BALB.B immune spleen cells were fused with a hypoxanthine aminopterin thymidinesensitive myeloma variant, M5, which was derived from SP2/0Agl4 as previously described (Harmon et al. 1983). Hybridomas were screened on C57BL/10J lyphoid cells by a modified complement-mediated microcytotoxicity assay, as previously described (Frelinger et al. 1974), and cloned by limiting dilution. The cell line 1.13 secreted the Ly-27.2-specific antibody. This immunoglobulin is a 72a~.
Ascitic fluid of monoclonal antibody Ly-27.2 was titrated by an antibody-mediated, complement-dependent cytotoxicity test on thymus, lymph node, spleen, and bone marrow cells. As shown in Figure 1, the Ly-27.2 antibody reacted with lymph node, spleen, and thymus tissue at a titer of approximately 1:150. Ly-27.2 antibody killed 40% of the spleen cells and 60% of the lymph node and thymus cells. Bone marrow cells were unreactive.
The lymphoid tissue distribution of Ly-27.2 reactivity determined by direct cytotoxicity analysis is shown in Table 1. Ly-27.2 antibody killed 60% of lymph node, 50%