Burkitt’s lymphoma-derived cell line, Raji, showed a cloning efficiency of 50%). These results are comparable to the lowest seeding regime used in this experiment and suggest that the medium used substantially affects clonal growth. Thus, the combination of an enriched medium and seeding the B cells directly onto a growing feeder layer clearly results in an improvement in cloning efficiency. Th...

Infection of human cancer xenografts in mice with murine leukemia viruses (MLVs) is a long-standing observation, but the likelihood of infection in vivo and its biological consequences are poorly understood. We therefore conducted a prospective study in commonly used xenograft recipient strains. From BALB/c nude mice engrafted with MCF7 human mammary carcinoma cells, we isolated a virus that wa...

Raji, a human B lymphoma line, expresses high levels of major histocompatibility complex (MHC) class II antigens. Conversely, none of the detectable human Ia antigens is present in RJ 2.2.5, an immunoselected Raji variant. Clonal analysis, biochemical characterization, and nucleic acid hybridization studies of hybrids between mouse spleen cells and RJ 2.2.5 show that MHC class II gene expressio...

Arsenic trioxide (As(2)O(3)) is an effective agent for the treatment of relapsed and refractory acute promyelocytic leukemia by induction of partial differentiation and apoptosis. As(2)O(3), at therapeutic concentrations (1-2 microM), induced apoptosis in Raji lymphoma cells but not in Jurkat lymphoma cells, which inversely correlated with the levels of glutathione-S-transferase pi (GSTP1), but...

Death-associated protein kinase (DAP-Kinase) is a novel serine/threonine kinase whose expression is required for g interferon-induced apoptosis. A previous study suggested that DAP-Kinase expression may be lost epigenetically in cancer cell lines, because treatment of several nonexpressing cell lines with 5-aza-28-deoxycytidine resulted in the expression of DAP-Kinase. Using methylation-specifi...

The B-cell CD20 antigen is one of the most reliable surface targets in immunotherapy of B lymphoma. In this project, we studied the production and characterization of a new monoclonal antibody against chimeric human CD20 extra loops (hCD20 exl). The results showed that clone C12H, IgG2/k isotype reacted with the antigen in ELISA and immunoblot. The Kd value was found to be 2×10(-9)M and flow cy...

RJ2.2.5, a mutant derived from the human B-lymphoma cell, Raji, is unable to express the MHC class II genes because of a recessive transcriptional defect attributed to the lack of an activator function. We report the isolation of a RJ2.2.5 revertant, namely AR, in which the expression of the mRNAs encoded by these genes is restored. Comparison of the binding of nuclear extracts or of partially ...