MEASUREMENT OF TRANSMITTED LIGHT AS AN INDICATOR OF CRYOPRESERVED PLATELET VIABILITY

This study was designed to establish an alternative technique to the m orphology scoring method described by Kunicki et al. [Transfusion 1975 ;15:414-421] using light transmission. A reference scale for platelet quality (expressed as a percentage of fresh cells) was established wit h a mixture of fresh platelets and damaged platelets frozen without cr yoprotectant. The transmittance, read against autologous plasma, was c ompared to morphology, hypotonic stress response (HSR) and ADP-induced aggregation. The results showed that transmittance, morphology and HS R were related linearly to the percentage of fresh platelets. There wa s a significant correlation between relative transmittance (RT) and mo rphology (r = 0.932), and RT and HSR (r = 0.91), but a very poor corre lation was found between transmittance and aggregation. Measurements o f transmittance provided an estimation of the global aspect of a popul ation of cryopreserved platelets in terms of shape, size and compositi on, and the relative transmittance of a sample to that of the fresh po pulation could predict morphology and HSR. It is concluded that these measurements offer a valid alternative method to the subjective morpho logy scoring obtained with cryopreserved platelets.