A simple and rapid treatment (trichloroacetic acid precipitation) of serum samples to prevent non-specific reactions in the immunoassay of a proteoglycan.

In our laboratory serum components interfering in the immunoassay of the schistosome proteoglycan circulating anodic antigen (CAA) in serum necessitated us to develop a simple technique by which the non-specific reaction of negative control sera could be prevented. Trichloroacetic acid was added to serum samples to precipitate interfering (glyco-)proteins. After centrifugation, the supernatant was neutralized and used directly either in the ELISA or in the indirect haemagglutination. This method gave satisfactory results, i.e., negative control sera did no longer give false positive reactions, while the titre of the positive controls remained unaffected. This method could also be successfully applied for the pretreatment of urine samples.