Treatment of donor T cell-mediated hematopoietic suppression after haploidentical bone marrow transplantation by T cell modulation in a patient with severe combined immunodeficiency.

An 8-month-old male patient with severe combined immunodeficiency syndrome was transplanted with maternal, haploidentical T cell-depleted bone marrow without prior conditioning therapy. Acute graft-versus-host disease developed 2 weeks post bone marrow transplantation (BMT) and was successfully treated with cortisone. After cortisone withdrawal the patient developed myeloid and B cell depression concomitant with T cell activation. For specific T cell modulation, treatment with the T cell receptor (TCR) alpha beta chain-binding MoAb BMA031 was initiated in combination with cyclosporin A. GM-CSF was given to enhance myeloid reconstitution. About 1 year post BMT, B cell and granulocyte counts were within the normal range with stable chimerism in both lineages. B cell proliferation tests were normal and first signs of in vitro immunoglobulin synthesis occurred.