We have measured immunoglobulin (Ig) synthesis by circulating lymphoid cells of 20 patients with cirrhotic hyperglobulinemia (CH) and 20 age-matched controls. We used specific anti-Ig antisera to precipitate Ig synthesized from [14C] amino acid precursors in 13 controls and employed an electroimmunoassay of the "rocket" type to measure Ig elaborated by cultured cells in 4 patient-control pairs. In addition, we studied 3 patient-control pairs by absorption of elaborated Ig onto an anti-Ig-coated solid phase, bromoacetylcellulose. The synthetic index (SI; the ratio of Ig synthesis by a CH patient and a control) was elevated in every case. Mean SI by coprecipitation was 7.2 +/- 5.4 (mean +/- SD), by rocket" 7.3 +/- 3.0 for IgG and 2.2 +/- 0.8 for IgA, and by immunoabsorption 13.8 +/- 8.4 for IgG. Three cirrhotic nonhyperglobulinemic patient-control pairs showed a mean SI of 1.0 +/- 0.1. CH and control populations showed equal numbers of membrane Ig-positive B lymphocytes by immunofluorescence. We conclude that (1) peripheral blood lymphoid cells are appropriate for study of differences in Ig synthetic capacity among individuals; (2) CH is associated with increased in vitro Ig synthesis; and (3) CH lymphocytes may be an appropriate cell population for the study of control mechanisms in Ig synthesis.