[The detection of rheumatic factors by means of a new hemagglutination drop test (Cellognost-RF)].

A comparative evaluation was made in 510 sera to study the specificity and sensitivity of 5 different methods for the determination of rheumatoid factors. Special attention was given to the hemagglutination drop tests which are commercially available (Cellognost-RF and Rheumaton). Both hemagglutination slide tests, which are easy to perform and easy to read, were shown to be practically equivalent, and in comparison to the other methods, also showed a good agreement. This is as well applicable to rheumatoid arthritis as to non-inflammatory processes and internal diseases. In practice, Cellognost-RF and analogous hemagglutination slide tests are certainly good screening tests for the rheumatic factors. In combination with the also simple latex-slidetest, the detection of rheumatoid factors in rheumatoid arthritis is somewhat better, although not much. When both reactions are negative, it is not necessary to do any additional tests for the demonstration of rheumatoid factors. Should one or both, however, be positive, the titre determination using the hemagglutination reaction of Waaler-Rose or latex fixation test should be made if possible. In our investigations it was also in principle possible to do these titre determinations with Cellognost-RF.