A Modification of the Hemagglutination Test for Rheumatoid Arthritis.

Abstract

The hemagglutination test for rheumatoid arthritis is modified by selective absorption of the natural nonspecific Forssman and heterophile antibodies, thus increasing the sensitivity and specificity of the test. The agglutination test involves mixtures of serially diluted rheumatoid arthritis serum, previously absorbed with washed sheep cells, and sheep cells sensitized with its amboceptor. The resulting titer reflects the agglutination factor associated with rheumatoid arthritis which is believed to display the properties of an antibody serologically specific for this disease. Comparative results are presented after testing sera from 166 patients by (a) the test as descr., (b) the original hemagglutination test, and (c) streptococcus agglutination test. Of 39 cases of active peripheral rheumatoid arthritis with X-ray evidence of joint changes, 35 cases (90%) were positive by the modified tests, 24 cases (61%) were positive by the original hemagglutination tests, and 23 cases (58%) were positive by the streptococcus agglutination tests. In all cases in which the modified tests were negative, the results from the other 2 methods were also negative. All cases of inactive peripheral rheumatoid arthritis, rheumatoid spondylitis without peripheral joint involvement and psoriatic arthritis tested were negative. The tests were negative in cases of equivocal early rheumatoid arthritis showing no X-ray evidence of joint changes. In a var. of nonrheumatoid arthropathies and miscellaneous medical disorders, the tests were negative except in 2 cases of infectious hepatitis where the sera tested showed low titer agglutinations.