A patient with long-standing rheumatoid arthritis developed hyperviscosity syndrome that correlated with the presence of abundant intermediate complexes in plasma. The intermediate complexes were isolated, and evidence is presented that these complexes are composed predominantly of IgG-rheumatoid factor.
Pope RM, Fletcher MA, Mamby A, Shapiro CM. Rheumatoid Arthritis Associated With Hyperviscosity Syndrome and Intermediate Complex Formation. Arch Intern Med. 1975;135(2):281-285. doi:10.1001/archinte.1975.00330020085011