[Anti-stratum corneum antibody in the rat esophagus, anti-epidermal keratin and anti-epidermis autoantibodies in rheumatoid polyarthritis and other rheumatic diseases. Diagnostic value and basic aspects].

Eight immunological parameters were explored in 257 patients with various rheumatic diseases including 107 rheumatoid arthritis (RA). IgG and IgM antibodies (AB) reactive with the Stratum Corneum (SC) of rat oesophagus or with the SC of human skin were assayed by 1/2 quantitative indirect immunofluorescence, IgG and IgM auto AB to epidermal keratins by a specific ELISA, and total serum G and M immunoglobulins by radial immunodiffusion. At the threshold we chose (99 p. cent specificity), IgG anti SC of rat oesophagus, were found in 50 of 107 (46.7 p. cent) RA patients: 52.5 p. cent in sero + and 39.6 p. cent in sero - ones. The other parameters, separately considered, had no diagnosis value. In Paget disease serum IgM and IgG and all the AB of M isotype were found to be broken down. In all the groups, the isotype AB were found strongly correlated to each other and to serum IgM. The RA sera with specific AB to the rat oesophagus SC, also labeled human skin SC but these labeling were unrelated to the anti-keratins auto AB level. On the contrary, the anti SC AB of G isotype, detectable on human skin in psoriatic rheumatism did not label rat oesophagus. These results confirm the diagnosis value of IgG AB to SC of rat oesophagus, usually called anti-keratins, who appear as a marker for RA. This work shows the relevance of associating specific immunochemical techniques to immunofluorescence, in order to unravel the antigenic complexity of tissular substrata.