Evaluation of a new test system for rubella haemagglutination inhibiting antibodies

A recently available kit for the determination of rubella haemagglutination inhibiting antibodies (Rubindex, Ortho diagnostics) was was compared with the method used routinely in this laboratory. Rubindex compared favourably in that no significant difference in titre was found in 95.1% of 287 sera tested. Difficulty occurred with some sera from cases of Mycoplasma pneumoniae infection, rheumatoid arthritis, and a small number of normal sera containing human "O" cell agglutinins. This was overcome by treatment of the sera with 2-mercaptoethanol. Rubindex had the advantage that all reagents were provided in kit form and the trypsinised human "O" cells provided had a longer shelf life than chick erythrocytes.