Isolation and immunological characterization of a group of new B lymphomas from CBA mice

We have isolated and characterized a new series of B lymphomas which occurred spontaneously in a group of CBA N mice that were transferred with spleen or lymph node cells from 24-month-old CBA Ca mice. Tumor cell lines from six CBA N mice that received spleen cells were rescued and designated as BKS-2, BKS-3, BKS-4, BKS-5, BKS-6, and BKS-7. Also, tumor cells from a recipient of lymph node cells were rescued and the resulting cell line was designated BKL. These tumor cells expressed membrane immunoglobulin (μ,κ), major histocompatibility complex Class I and Class II molecules, B220, Lyb8, Fc receptors, J11d, interleukin 2 receptors, and Ly1. All of the tumors did not express the T cell specific markers Thy 1.2, L3T4, and Lyt2.1. They appeared to be clonal in origin, since they exhibited common rearrangements at both heavy and light chain immunoglobulin loci. Phenotypically, these lymphomas appeared to be analogous to immature B cells. Also, these lymphomas displayed different functional reactivities when treated with various B cell mitogens and growth factors in vitro. Anti-μ antibodies which normally induce B cell growth inhibited the proliferation of these lymphoma cells in vitro, whereas they responded to lipopolysaccharide, T cell-derived growth factors, and interleukin 5 by enhanced proliferation. These tumor cells expressed constitutively high levels of c-myc mRNA.