Clinical Problems Associated with T Cell Depletion for Bone Marrow Transplantationa

Enhancement of bone marrow allografts from nude mice into mismatched recipients by T cells void of graft-versus-host activity.

“…These results would suggest either that treatment with this antibody was especially toxic to pluripotent bone marrow stem cells or that BT5/9' T cells may play an important regulatory role in bone marrow engraftment. Bacigalupo et al (24) support the latter possibility, as removal of BT5/9' T cells does not affect the growth of myeloid or erythroid colonies in vitro.…”

“…They took extra care to drastically purge T cells from their bone marrow preparations, and it is possible that this led to the higher rate (over 50%) of graft rejection experienced in their series compared to what is commonly found in other centers using less-extensive T-cell depletion. At the other extreme, Bacigalupo et al (24) reported the results of clinical trials involving partial T-cell depletion that made use of a mouse monoclonal antibody (anti-BT5/9, specific for 15% of peripheral blood T cells and 5-10% of bone marrow T cells; CD not yet defined) (25) to eliminate only a small subset of inducer/helper T cells. Surprisingly, the incidence of graft failure and leukemia relapse was significantly higher among these patients than among those treated at other centers with conventional T-cell depletion techniques that used pan-T-cell antibodies.…”