It is concluded that a medium composed of 15 per cent Dimethylsulfoxide and 85 per cent of a mixture of equal parts native plasma and saline effectively preserves platelet lactic acid dehydrogenase activity against slow freezing, storage for 24 hours in temperatures of liquid N2 and fast thawing. Platelet lysis results in a complete loss of LDH activity.
The clot retracting activity (CRA) of frozen platelets was studied as the in vitro test best representing the functional "integrity" of platelets. Dimethylsulfoxide as an additive in the preservation by freezing of platelets acts most effectively in the presence of plasma. Freezing of the platelets in a suspending medium consisting of 50 per cent plasma in saline with 15 per cent DMS, resulted in a 10 to 15 per cent loss over the fresh control CRA values. Freezing rates ranging from 3 C. to 30 C. per minute can be used without modifying the final result. Storage in liquid nitrogen for 38 days resulted in a 34 per cent CRA reduction over the frozen but not stored platelets. These results seem to justify trials of the in ~i v o survival of platelets preserved by these methods.
The Good family, in which the husband's red blood cells contain a private antigen (Good) responsible for the development of severe erythroblastosis fetalis in four infants, has had two additional infants since the original reports in 1960 and 1961. The latest pregnancy, which terminated in 1965, permitted further evaluation of both the Good antigen and anti‐Good. The antibody has been found in 0.3% of sera of a random donor population (eight examples in 2,718 donors). No additional example of the antigen has been found in 2,382 random donors. Spectrophotometric analysis of amniotic fluid was used in management of the latest pregnancy, which resulted in a normal unaffected infant.
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