Evaluation of a new UVB source for irradiation of platelet concentrates

The application of ultraviolet B (UVB) radiation has been proposed as a new technology to decrease immunogenicity of leucocytes in platelet transfusions. UV radiation also induces platelet aggregation, which occurs most effectively at wavelengths between 240 and 280 nm and falls off sharply above 300 nm. In order to minimize the effects of UV energy on the platelets we evaluated in this study the expected benefit of a new narrow-band UVB source, emitting a narrow peak around 312 nm. Exposure of platelet or lymphocyte suspensions to this source induced in the platelets both aggregation and functional defects at a dose of 12 J/cm2 and in the lymphocytes inhibition of in vitro function at a dose of 2 J/cm2. A conventional UVB source, emitting a broad spectrum between 280 and 340 nm, was more deleterious for the cells and induced similar defects in the platelets at a dose of 6 J/cm2 and inhibition of lymphocyte function at a dose of 1 J/cm2. These data indicate no benefit for the new UVB source, since the ratio of the doses to induce platelet defects and inhibition of lymphocyte function is identical for each of the two sources. Absorption of UV energy by plasma and the plastic material of platelet containers is another criterium for selection of UV sources. In view of the better transmission characteristics of long wavelength UV energy we propose that there is a preference for the new narrow-band UVB source.