An ELISA for IgA, IgG and IgM-RF measurement. I. Parameters of the assay.

A simple and rapid solid phase ELISA for the stepless determination of IgA, IgG and IgM-RF was developed. The ELISA works with Fc parts of human IgG as antigen. Specificity, validity and precision were tested. RF complex dissociation by urea and separation by gel filtration was performed in several samples to obtain information of the transfer of non-RF-IgG by pentameric IgM-RF. The RF-ELISA may give better information on the significance of RF of the three Ig classes in the clinical course of RA.