| Abstract: | Titration of anti-complementary human sera may yield false negative or prozone reactions in anti-complement immunofluorescence (ACIF) tests for antibodies to Epstein-Barr virus-associated nuclear antigen (EBNA) when the human complement (C') is added to the serum dilutions prior to charging of the target cell smears (two-stage ACIF test). This effect of anti-complementary sera and with it a source of error is avoided by using a three-stage ACIF technique; that is, when the target cell smears are successively overlayed with serum dilutions, C' and fluorescein isothiocyanate-conjugated antibodies to human βC/βA globulins. The two- and three-stage ACIF procedures yield comparable anti-EBNA titers with non-anti-complementary sera. |
