A simple, rapid micro-latex fixation test.

SUMMARY Amicro-latex fixation test (LFT) for the determination ofrheumatoid factor (RF) is presented.Its advantages compared to similar tests are greater precision, simplicity, increased sensitivity,lowercost, reproducibility and adaptibility to large-scale testing. Micro-LFTtitres are presented from a wide range of sample populations. The majority of normal samples show measureabletitres whereasrheumatoid patients show high titres. A large sampling ofpre-and post-transplant sera from kidney patients was studied and the micro-LFT titres were in the range ofnormalpersons. The transplant sera were tested for lymphocytotoxic antibodies and no correlation was observedwiththemicro-LFTtitres.INTRODUCTIONThelatex fixation test (LFT) introduced in 1956 is the most widely used method for determination ofrheumatoid factor (RF) (Singer & Plotz, 1956). Some modifications of the test have been proposed, such as the use of aggregated IgG(Singer et al., 1960) and more recently, the nephelometric