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Graft-versus-host disease (OVHD) after allogeneic bone marrow transplantation (BMT) is initialed by immunocompetent T cells present in the graft. Selective elimination of distinct T-cell subsets or a sufficient, but not complete T-cell depletion, might abolish severe GVHD without graft rejection and loss of the anti-tumour potential. In this study we analysed the efficacy of different monoclonal antibodies (MoAb) WT32 (CD3). OKT4 (CD4), T101 (CD5), WT1 (CD7), and WT82 (CD8) with respect to their cytotoxicity to T cells either as immunotoxin (IT) or in combination with complement. The cytotoxic potential was assessed by protein synthesis inhibition and clonogenic assays. The ricin A conjugated MoAb exerted only a minor effect on blood or bone marrow T cells, although they were highly inhibitory to T-cell lines. However, in the presence of 20 mM ammonium chloride. IT directed against CD3, CD5, and CD7 were highly cytotoxic. IT directed against CD4 and CDS were less effective, due to a low internalization. The complement-mediated cytotoxicity was efficient for all antigens used. The natural killer (NK) activity, as measured by cytotoxicity to K562, was hardly depressed by anti-CD3, anti-CD4, anti CD5, and anti-CD8, but was eliminated by anti-CD7. All procedures used had only a minimal effect on haematopoietic progenitors us measured by CFU-GM and BFU-E assays. We concluded that, although the T-cell population can be eliminated with the combination of anti-CD3, anti-CD5, and anti-CD7 antibodies plus complement, IT with 20 mM NH4Cl appear to kill higher amounts of T cells. Selective elimination of CD4- and CD5-positive cells is effectively obtained by MoAb with complement. [ABSTRACT FROM AUTHOR]

The Raji-cell test is one of the most widely used methods for the detection and quantitation of immune complexes. Immune complexes and not 7 S IgG bind via C3 to complement receptors on the cell membrane of the Raji cell, During sucrose gradient fractionation of human and murine systemic lupus erythematosus sera, with a high Raji cell-binding activity, we could not demonstrate immune complexes in these sera. Subsequent analysis showed that the major part of the Raji cell binding was used by 7 S IgG with an anti-DNA specificity. Blocking experiments with complement-bearing aggregated IgG revealed that complenicni and Fc receptors were not involved in the binding of these anti-DNA antibodies to Raji cells. We conclude that the Raji cell test is not suitable for the detection and quantitation of immune complexes in sera containing anti-DNA antibodies. [ABSTRACT FROM AUTHOR]