Human marrow T cell dose correlates with severity of subsequent acute graft-versus-host disease.

Sixteen patients with haematological malignancy received high-dose chemotherapy or chemotherapy and total body irradiation followed by an HLA-identical sibling marrow transplant from which the T lymphocytes had been depleted prior to infusion by incubation with an anti-CD2 anti-T cell antibody with (seven patients) or without (nine patients) an anti-CD8 anti-T cell antibody together with rabbit complement. Additionally, all patients received cyclosporin. The number of T cells present in the donor marrow was determined by limiting dilution analysis, and was found to correlate with the subsequent incidence and severity of acute graft-versus-host disease (GVHD). The number of T cells infused into patients with no acute GVHD or with minimal acute GVHD of the skin (skin rash present for 14 days or less) was 1.3 +/- 1.0 x 10(5)/kg, while the number infused into those with moderate acute GVHD or with skin acute GVHD present for 15 days or more was 12.3 +/- 11.5 x 10(5)/kg (p less than 0.001). Thus a dose of 10(5) (or less) T cells/kg was associated with minimal or no acute GVHD, while 10(6) T cells/kg (or more) caused significant disease.