CD48 Monoclonal Antibody K31 for Bone Marrow Transplantation: Functional Characteristics
In clinical bone marrow (BM) transplantation, graft-versus-host reaction can be effectively prevented by depleting the graft of T cells. However, transplantation of T-depleted grafts is complicated by a high incidence of graft rejection due to residual immunological reactivity of the host and the immunogenicity of the graft . Recent reports suggest that the immunogenicity of an organ graft is largely due to BM-derived “accessory cells” (AC) that are distributed in the organ, whereas the cells that are essential for the graft’s function do not play nearly as important a role in immunogenicity . In this context, we have been able to demonstrate that the CD48 monoclonal antibody (MoAb) K31 binds to almost all human lymphoid cells, and, in addition, to macrophage cells with high accessory capacity, such as monocytes, dendritic cells, and veiled accessory cells. On the other hand, no other hemopoietic or nonhemopietic cells, including progenitors, are labeled by K31 [3,4]. In the present paper, we report that K31 is cytotoxic with rabbit complement (C) but not with human C. Because it completely eliminates BM AC, K31 + C strongly reduces the allostimulatory capacity and thus the immunogenicity of BM mononuclear cells (BMNC). In contrast, the CDw52 MoAb CAMPATH-1 or T cell-specific MoAbs do not affect BM immunogenicity.
KeywordsAccessory Cell Bone Marrow Mononuclear Cell CD48 Monoclonal Antibody 51Cr Release Human Lymphoid Cell
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