Standard Cryoprecipitate was prepared from fresh citrate phosphatedextrose plasma by snap freezing at —70° C and then thawing at +4° C in air for 18 hours. In 143 experiments the yield of Factor VIII from the starting plasma was 42%.In 64 paired experiments the Factor VIII yield in Cryoprecipitate from fresh plasma was increased, from 43% in the standard method to 56% when a quick thaw of 50 minutes at +4° C in a liquid bath was introduced. In 10 other paired experiments the yield in the standard method was raised from 51% to 61% when 90 minutes of super-cooling at —6° C in a liquid bath was introduced prior to snap freezing. When, however, the quick thaw and super-cooling modifications were combined in 42 paired experiments, the yield was only 49% compared with 42% by the standard method.It is concluded that this simple quick thaw modification will produce a greater yield of Factor VIII in Cryoprecipitate and that the addition of the technically more demanding super-cooling modification does not give a significantly greater yield.It seems likely that the longer period at +4° C in the standard method leads to denaturation of a proportion of the Factor VIII and loss of activity. Factor VIII antigen, however, was not lost. In a smaller number of experiments approximately all the Factor VIII was recovered in the Cryoprecipitate and its supernatant. Furthermore, the relative proportions of Factor VIII antigen and procoagulant in the Cryoprecipitate were found to vary in concert suggesting that the Factor VIII molecule is not dissociated in the process of cryoprecipitation.
Mechanism of Liquid Bridges Stretched out of a Liquid Bath
