[Immunological diagnosis of collagen diseases and rheumatoid arthritis (author's transl)].

Most helpful immunological tests for diagnosis of connectivities are revised. Among them, antinuclear antibodies (AAN) are the most important. They are usually detected by immunofluorescence and show different patterns, being the peripheral one the most specific of SLE and it is related with antibodies anti-DNA which can make immunocomplexes DNA-anti-DNA and be the cause of lupic nephropathy. The "nucleolar" and "speckled" patterns are more frequent in scleroderma. The LE cells have less value than AAN. The rheumatoid factor is a IgM antibody anti-IgG, but also can be of IgG or IgA class. It is uncommon in the juvenile rheumatoid arthritis of systemic onset and more frequent in oligoarticular adult type. May became positive during disease evolution. Other factors as immunoglobulin of complement usually are increased, except when the activation of complement take place. Acute phase reactants are helpful just for evaluating the importance of inflammation, they have not diagnosis value and commonly do not exceed the value of erythrocyte sedimentation rate.