Selective CD4+ T-cell depletion does not prevent graft-versus-host disease

Donor-derived CD4(+) T cells may play a role in the development of graft-versus-host disease (GVHD) and graft-versus-leukemia reaction after allogeneic bone marrow transplantation (BMT), Therefore, we evaluated the effect of CD4(+) T-cell depletion on GVHD and graft-versus-leukemia reaction after HLA-matched BMT, CD4 depletion was performed using anti-CD4 monoclonal antibodies and immunomagnetic beads, initially in small-scale experiments on bone marrow and granulocyte colony-stimulating factor-mobilized peripheral blood apheresis products. The result was elimination of the CD4(+) T cells from both sources (0% and 2+/-1.4% CD4(+) cells, respectively). Subsequently, we used this technique for large-scale negative selection of CD4(+) T cells from bone marrow grafts of four consenting leukemic patients in relapse (ALL-3, ANLL-1) (M-3, F-l), The large scale CD4(+) T-cell depletion resulted in >98% (n=4) elimination of CD4(+) cells. The resulting population included 17.7+/-4.6% CD3(+) T cells, 8.9+/-2.5% CD8(+) T cells, 0.1+/-0.1% CD16(+) natural killer cells, and 2.3+/-3.2% CD34(+) hematopoietic progenitor cells. Patients were transplanted with 2.84+/-1.31x10(8) viable cells/kg, They received cyclosporine starting on day -1 as GVHD prophylaxis. Engraftment was fast with a white blood cell count of >1x10(9)/L on day 13.2+/-0.5, an absolute neutrophil count of >0.5x10(9)/L on day 13.8+/-0.5, and a platelet count of >25x10(9)/L on day 26.5+/-6.8. Immunological reconstitution was normal, and peripheral blood phenotyping 3 weeks after BRIT disclosed 49.0+/-5.0% CD3, 14.3+/-12.4% CD4, and 59.5+/-7.8% CD8(+) T cells in addition to 17.0+/-3.0% CD16(+) and 9.0+/-3.0% CD56 natural killer cells. Three out of four patients developed very early grade TV GVHD beginning on day 12 (10-13) and died 2-4 months after BRIT, One patient is alive and well with a follow-up of 36 months, We conclude that selective CD4 T-cell depletion does not prevent GVHD.