Subtyping of Hepatitis B Antigen by Use of Monospecific Antibody-coated Cells

Abstract

A sensitive red cell agglutination (RCA) method for the detection of hepatitis B antigen (HB Ag) was adapted for subtyping. The technique used human type 0, Rh-negative erythrocytes stabilized with pyruvaldehyde and formaldehyde and coated with IgG containing monospecific anti-d or anti-y hepatitis B antibody prepared from antiserum produced in guinea pigs. Optimal coating of stabilized erythrocytes occurred at 25 C and at pH 4.0 with a concentration of IgG of 0.25–0.5 mg/ml and a 60-min incubation period. The coated cells were stable for at least one month when stored at 4 C or for at least four months when frozen at −70 C or −196 C. The RCA test was conducted at 25 C and read after 3 hr. Nonspecific agglutination was not observed at serum dilutions of ⩾ 1: 10. Results were verified by agar gel diffusion or by a more sensitive double antibody radioimmunoassay method that was modified to detect subspecificities of HB Ag. HB Ag endpoint titrations can be obtained within 3 hr, and the test is 100- to 200-fold more sensitive than the agar gel diffusion technique.