[Enzyme histochemical demonstration of immunoglobulins in joint capsules in chronic polyarthritis and active...

In rheumatoid arthritis, immunoglobulins are detectable in joint capsules within the subsynovial space and in superficial cell layers in significantly greater frequency as compared with osteoarthritis. These extravascular immunoglobulins were demonstrated in good agreement by a three-step immuno-peroxydase technique and a two-step alkaline phosphatase technique, the former being preferable because of reduced unspecific background staining. Both techniques are at least as sensitive as conventional immunofluorescence while in addition rendering the histological evaluation of the entire joint capsule possible. Thus, the detection of extravascular immunoglobulins can be related to their activity as mediators of inflammation. Accordingly, hypertrophy and hyperplasia of superficial cells as well as stromal proliferation could be consequences of immunoglobulins or immune-complexes persisting in the joint capsule. The histochemical techniques described here are suitable to morphologically distinguish osteoarthritis from chronic polyarthritis in histological sections. The presence of immunoglobulins in superficial cell layers and/or extravascular spaces argues in favour of rheumatoid arthritis.