[The effect of Campath-1 on T- and NK-cells]

An assay system capable of detecting 0.03% residual T cells is described. This test system was used to evaluate bone marrow which was treated with Campath-1 and human complement (HC'). All T cell-depleted samples tested were found to be free of OKT3-positive T cells (less than 0.03%). The assay described provides a highly sensitive method for the detection of residual T cells and can be used as an alternative to limiting dilution assays. The results presented here confirm that treatment of donor bone marrow with Campath-1 and HC' provides a highly effective means of removing T cells and thus should be effective in GVHD prevention. However, although Campath-1 effectively depletes T- and B cells, it unexpectedly failed to eliminate cells that display NK function.