Serum immunoglobulins in juvenile rheumatoid arthritis.

Juvenile rheumatoid arthritis (JRA) differs in many aspects from its adult counterpart (Edstrom, 1958); one of the differences is a low incidence of positive sero-reactions for rheumatoid factors (RF) in patients with JRA (Bywaters, Carter, and Scott, 1959; Sievers, Ahvonen, Aho, and Wager, 1963; Ansell, 1966). Although the agglutinating activity of RF was found in different classes of immunoglobulins (IgC, IgA, IgM), the typical representative ofRF is IgM (McCormick, 1966). However, there is no direct correlation between the IgM values and the presence or absence of RF in the serum of patients with rheumatoid arthritis (Claman and Merrill, 1966; Barden, Mullinax, and Waller, 1967; Marcolongo, Carcassi, Frullini, Bianco, and Bravi, 1967). The purpose of this paper was to study the serum levels of immunoglobulins (IgG, IgA, IgM) and to compare them with serological RF-positivity in the serum of patients with JRA.