Use of indirect microhemagglutination test with stable sensitized red cells in the detection of horse protein allergy

Sheep red blood cells were stabilized with sulfosalicylic acid and sensitized with purified horse-IgG by the action of glutardialdehyde. The cells were used in an indirect microhemagglutination test with serum samples from 12 rabbits immunized with horse-IgG and complete Freund's adjuvant as well as from 10 control animals. 32 human serum samples were examined, 6 of them from patients with established horse protein allergy. The results were compared to those of a standard method of indirect hemagglutination using fresh human erythrocytes (group O Rh-), an active hemagglutination test against horse erythrocytes, Ouchter-lony's immunodiffusion and skin tests with horse-IgG. The method proved to be very sensitive. The results correlated well with those of the other immunological techniques. The stable sensitized cells did not lose sensitivity after 1 year of storage at 4 °C.