COMPARISON OF CAMPATH-1 PLUS COMPLEMENT, ANTI-T CELL RICIN A CHAIN IMMUNOTOXIN, AND SOYBEAN AGGLUTININ ALONE OR IN COMBINATION WITH SHEEP ERYTHROCYTES OR IMMUNOMAGNETIC BEADS

Publisher Website
Google Scholar
Abstract
The aim of this study was to compare the extent of in vitro T cell depletion and recovery of hematopoietic progenitor cells achieved with five methods of T cell depletion. Bone marow samples from the same source were treated with monoclonal antibody Campath-1 (CP1) and human complement, XomaZyme-H65 (anti-T cell rich A chain immunotoxin) or soybean agglutinin (SBA) alone or in combination with sheep erythrocytes (EAET) or a cocktail of immunomagnetic beads (B) directly coated iwth anti-CD2, anti-CD3, or anti-CD8 monoclonal antibodies. Residual T cells were enumerated by limiting dilution analysis, EAET rosetting, and proliferative responses to phytohemaglutinin. The results of this study demonstrated the following reductions in BM T cells as detected by limiting dilution analysis (mean % control): SBA+B (99.9%), SBA+EAET (99.8%), CP1+C'' (99.4%), anti-T cell ricin A chain immunotoxin (99.0%), and SBA alone (94.2%). Neither PHA respone nor enumeration of residual EAET rosettes provided discriminating differences in the degree of T cell depletion by treatment method when T cell reductions exceeded 99.0% by LDA. These results demonstrate the ability of CP1+C'', Xoma Zyme-H65, and SBA plus sheep erythrocyte or magnetic bead depletion to achieve a greater than 99% reduction of BM T cells and the importance of limiting dilution analysis in defining differences in T cell numbers when depletion exceeded 99%.