In a case of infantile syphilis, evaluation of the complement fixation test for syphilis was difficult because of an anticomplementary effect caused by cryoglobulin. The anticomplementary effect was not removed even after heating the serum at 56 C for 30 minutes; the supernatant was used for the test after keeping it at 5 C for 18 hours. Cryoglobulin disappeared following administration of penicillin G procaine.
Watanabe S, Watanabe S. Infantile Syphilis Accompanied by Anticomplementary Effect of CryoglobulinReport of a Case. Arch Dermatol. 1974;109(6):889. doi:10.1001/archderm.1974.01630060065019