Impact on T-cell depletion and CD34(+) cell recovery using humanised CD52 monoclonal antibody (CAMPATH-1H) in BM and PSBC collections; comparison with CAMPATH-1M and CAMPATH-1G

Background Ex vivo T-cell depletion of allogeneic BM (BM) grafts can effectively reduc e graft versus host disease (GvHD) and may also apply to transplantation of allogeneic peripheral blood stem cell (PBSC) transplants. Methods Here we have evaluated T-cell depletion and progenitor cell recovery by ant ibody-mediated cells lysis using three CD52 monoclonal antibodies (MAbs) at different concentrations and cell densities. Results CAMPATH-1M was superior to CAMPATH-1H for T-cell depletion of BM samples. T reatment with CAMPATH-1M resulted in up to 2.55 log depletion of CD3(+) cel ls, with recoveries of greater than or equal to 45% CD34(+) cells, greater than or equal to 67% CFU-GM and greater than or equal to 65% BFU-E. CAMPATH -1H treatment resulted in up to 1.64 log depletion of CD3(+) cells and simi lar recoveries of CD34(+) cells, CFU-GM and BFU-E as seen with CAMPATH-1M. Depletion of CD19(+) cells was similar to that observed for CD3(+) cells wh ile natural killer (NK) cells were relatively spared compared with the T an d B cell populations Log depletions of T cells from PBSC, as determined by immunofluorescence studies and limiting dilution analyses, were similar usi ng CAMPATH-1M, -1H, and -1G. There were also no differences in the depletio n of CD19(+) cells or NK cells using the three MAbs. Similar results were o btained for recoveries of CD34(+) cells, CFU-GM and BFU-E using all three M Abs, although the recovery of CD34(+) cells using the highest concentration of MAbs was significantly greater in CAMPATH1H treated samples Increasing the number of PBSC treated with CAMPATH-1H and -1M had no effect on the log depletion of T, B or NK cells and there were no major differences in the l og depletions achieved with CAMPATH-1H or -1M. Likewise, the higher PBSC de nsity had no effect on the recoveries of CD34(+) cells or committed progeni tors and once again CAMPATH-1H gave similar recoveries to those obtained us ing CAMPATH-1M. Discussion Although CAMPATH-1M resulted in greater ex vivo T-cell depletion of BM than CAMPATH-1H, in all other respects the humanised CAMPATH-1H was just as eff ective as CAMPATH-1M and -1G.