Ability of C . B - 20 Mice

The BCL1 tumor is a B cell neoplasm that causes massive splenomegaly and leukemia in BALB/c (Ig-1 a) mice (1). The tumor cells bear IgM and IgD on their surface and are phenotypically and functionally analogous to immature B cells (2). When mice from an allotype-congenic strain, C.B-20 (Ig-l~), are injected with 10 °107 BCL1 cells, they are resistant to tumor growth (3). These mice generate T cells that can adoptively transfer tumor immunity to sublethally irradiated C.B-20 recipients. Upon in vitro rechallenge of their spleen cells, cytotoxic effector cell activity is generated that is directed against antigens on BALB/c lymphoblast target cells as well as on BCLt cells (3). Little information is available on the role of cytotoxic T cells in regulating B cell neoplasms. Abbas et al. (4) described effector cells that inhibited M O P C 315 secretion in vitro. These cells were phenotypically characteristic of cytotoxic T lymphocytes (CTL)) However, their specifcity was directed against the myeloma's ligand, trinitrophenol, rather than against immunoglobulin (Ig) itself. Most C T L activity that has been described is directed against viral antigens, minor H antigens, or haptens covalently coupled to cell membranes (5, 6). With the exception of trinitrophenylated proteins (7-9), C T L apparently display specificity for integral membrane proteins or molecules that can fuse with the plasma membrane (10). Accordingly, C T L could potentially be generated against surface Ig (sIg) determinants. In this regard, Rolink et al. (11) generated C T L using allotype congenic strains. However, the antigen(s) recognized by their effector cells were detected on a T cell tumor as well as both T and B lymphoblasts and presumably represent minor H antigens. In this report we have determined the specifity of C.B-20 anti-BALB/c (anti-Ig H) cytotoxic effector cells as well as the tissue distribution of the antigen(s) recognized by these effector cells. The simplest interpretation of our data is that the effector cells recognize either the constant portion of the # and/or 8 heavy chain on Ig or a molecule coordinately expressed on sIg + cells.