RUBELLA ANTIBODY DETERMINATIONS

Abstract

Four methods were used to determine rubella antibody titers in patients with acquired and congenital rubella and in gamma-globulin. These methods include hemagglutination inhibition (HI), neutralization (Neut), fluorescence (FA), and complement fixation (CF). With acquired rubella, all four methods showed a rapid development of antibody shortly after the occurrence of rash. Maximum titers appeared within a few weeks, following which HI and CF titers began to decrease and the FA tests showed a weakening of fluorescence. HI titers were four- to sixteenfold higher than Neut, FA, and CF levels. Ten or 20 years after rubella, HI, Neut, and FA tests continued to show detectable antibody but half of the patients no longer had CF antibody. HI titers were still higher than Neut and FA but were considerably lower than convalescent levels. There was complete agreement between HI and Neut tests in the detection of antibody in young adults. For congenital rubella, HI, Neut, and FA antibody persisted in the affected children at least through adolescence. HI and CF antibody increased occasionally during the period 8 to 12 months after birth. Gamma-globulin titers with the HI and Neut methods were in close agreement. Convalescent rubella gamma-globulin gave titers two- to fourfold higher than standard commercial gamma-globulin. Variations in the HA and HI tests were caused by modification of the method of treatment of the antigen, the concentration of red cells used, the size of the test (macro versus micro), the pH of the test, and the treatment of sera. The most significant effects were related to the treatment used to eliminate nonspecific inhibitors in the sera. Improper treatment can give false negative or false positive tests. When properly performed and appropriately controlled, the HI test gives results essentially identical to the Neut method, although the titers are consistently higher than the Neut test. This new method, then, is rapid and convenient for obtaining reliable information on the antibody status and susceptibility of patients.