Immunologic parameters in infective endocarditis: a prospective study.

ABSTRACT

To evaluate the role of immunoglobulins, complement, circulating immune complexes (CIC), heart antibodies (HAb) and rheumatoid factor (RF) in infective endocarditis, we studied 28 consecutive patients before and after therapy. Statistically significant elevation was seen in IgG (p less than 0.001) and IgA (P less than 0.001) level prior to initiation of therapy as compared to a control group. Following drug treatment a fall was noted in IgA (P less than 0.01) and IgM (p less than 0.01) level as compared to basal values. Low C3 levels were seen in those with renal involvement (p less than 0.05). CIC levels estimated by 4% PEG precipitation assay were found to be elevated in 64% of patients. Patients with shorter duration of illness (less than three months) had higher levels of CIC containing IgG (P less than 0.005), IgA (P less than 0.05) and IgM (P less than 0.05), as compared to those with a longer duration. Initial CIC levels did not predict the clinical course and were found to be of no value in prognosis, although an improvement in congestive heart failure was associated with a rise in C3 (P less than 0.05) and IgM (P less than 0.05) containing CIC and an overall clinical improvement with a rise in IgA (p less than 0.05) containing CIC. There was no statistically significant difference in CIC level, for the entire group studied, before and after therapy. Patients who had rheumatoid factor in their initial serum sample demonstrated a fall in IgG, IgA and IgM containing CIC and a rise in C3 with therapy. The converse was true for those who lacked RF.(ABSTRACT TRUNCATED AT 250 WORDS)