Ultraviolet irradiation modulates MHC-alloreactive cytotoxic T-cell precursors involved in the onset of graft-versus-host disease.

Ultraviolet B (UVB) irradiation of cellular blood components has been proposed as a new technology to prevent HLA sensitization in recipients. Earlier studies have shown that a dose of 2 J/cm2 abrogates the ability of lymphocytes to serve as stimulators in mixed lymphocyte cultures (MLC). In this study we have evaluated the effect of UV energy on T-lymphocytes for the prevention of transfusion-associated graft-versus-host disease (TA-GvHD). The response of cytotoxic T-lymphocyte precursors against host alloantigens was almost undetectable at a dose of 0.5 J/cm2. T-cell proliferation in MLC or in response to phytohaemagglutinin was inhibited by more than 95% at doses of 1 J/cm2 or higher. The data suggest that UV irradiation can be used to prevent both HLA sensitization and TA-GvHD in recipients.