Further assessment of cardiolipin antigen by parallel testing against standard antigen in routine Wassermann reactions.

In a previous communication (Shaw, 1955), I referred to several papers concerning the value of cardiolipin antigen in complement-fixation and flocculation tests. The majority of workers have reported increased sensitivity and specificity with this antigen, which has also been recommended to obtain reproducible results in various laboratories in different countries. At that time, I compared the results of over 7,000 complement-fixation tests using cardiolipin and crude heart antigens in parallel tests. The results showed that cardiolipin antigen gave increased sensitivity, especially with early syphilis and treated syphilis, but gave more non-specific reactions which were most evident with antenatal sera. In this previous series, the crude heart antigen, designated as standard antigen, was used at a dilution of 1/15 in saline as in Harrison and Wyler's technique. The cardiolipin antigen was Burroughs Wellcome Whitechapel Clinic Formula, used at optimum titre.