Levels of serum immunoglobulins in patients with rheumatoid arthritis.

Quantitative and qualitative modifications of the plasma proteins are of particular importance among the systemic manifestations of rheumatoid arthritis. Increase of a2and y-globulins may be found in most patients (Ropes, Perlmann, Kaufman, and Bauer, 1954) in relation to the onset, evolution, and activity of the disease (Bonomo, 1957). The most important pattern consists generally of a predominant hypergammaglobulinaemia, but this may not be considered a specific finding of rheumatoid arthritis because it is a common serological pattern of many diseases involving chronic inflammatory processes (Bonomo, 1957; Claman and Merrill, 1965). This indicated that a more thorough survey of this globulin fraction, which is carrier of nearly all the serum antibody activity (Heremans, 1960), should be undertaken. The serum gammaglobulins form a heterogenous system and the main components (yG, yA, yM, and yD) can be distinguished on the basis of different antigenic groups (Heremans, 1960; Fahey, 1962; Claman and Merrill, 1964; Fahey and McKelvey, 1965). Immuno-electrophoresis is a useful method of separating fractions and evaluating the presence and the nature of any abnormal components in the serum, but this technique is based on a semi-quantitative method and may not give precise quantitative indications of the changes in each of the fractions. Recently, by using the radial immunodiffusion technique, it has been possible to study and estimate quantitatively each single gammaglobulin fraction by means of specific anti-sera directed against the corresponding antigenic group (Heremans, Vaerman, Carbonara, Rodhain, and Heremans, 1963; Claman and Merrill, 1964). The purpose of this paper is to study the sera of patients with rheumatoid arthritis by means of immuno-electrophoresis on agar and immunodiffusion methods to define alterations immunologically and to establish their specificity and their relationship with the activity and duration of the disease. Moreover, it appeared to be of interest to check in the tested sera the possible relations between the levels of yM fraction, to which rheumatoid factor belongs, and the positivity of the agglutination reaction.