Increased antibodies to IgG fragments: Correlation with infection due to gram-positive bacteria

The clinical and laboratory findings in 35 patients with severe infections and 102 patients who were selected for hyperglobulinemia were carefully reviewed and correlated with levels of serum agglutinators (antibodies to IgG Fab fragments) and rheumatoid factors (antibodies to IgG Fe fragments). Suppurative infections due to gram-positive cocci were found to be associated with high titers of serum agglutinators, whereas infections due to gram-negative bacilli, viruses, fungi, or mycoplasmas were not. Positive slide tests for rheumatoid factors were associated with hyperglobulinemia but not with severe infection. Rheumatoid factors have been demonstrated in a variety of diverse states of disease [1], and the association of these antibodies to globulin with in-fections of known and precise etiology has aroused particular attention [2, 3]. Although low titers of these antibodies have been found in a wide variety of diseases as well as in normal individuals [4], titers comparable to those seen in rheumatoid ar-thritis are rarely encountered. Although the bio-logic significance of these factors is unknown, a growing body of evidence suggests that in high titer they are merely an exuberant response of a group of normal heterophile antibodies to globulin [5]. Pathogenic effects of these antibodies have never been unequivocally demonstrated. Recently, another group of antibodies to glob-ulin, distinct from rheumatoid factors and known as serum agglutinators, has attracted considerable interest [6, 7]. These antibodies were first reported Received for publication May 24, 1971, and in revise