Types of immune complexes in the ascitic fluid of women with carcinoma of the ovary.

Immune complexes with C1q-fixing properties and those precipitable by polyethylene glycol (PEG) were detected in ascitic fluid from patients with advanced ovarian cancer. The ascitic fluid from 42 of 58 patients (72%) contained these complexes. A positive result with the C1q assay was obtained in 41% of patients, whilst with the PEG assay a positive result was obtained in 59% (50% in the IgM, 36% in the IgG, and 14% in the IgA fraction). The highest mean level of PEG-precipitable complexes was in the IgG fraction (11.4 mg/100 ml) and lowest in the IgA fraction (3.3 mg/100 ml). These results indicate that gram quantities of the immune complexes may be isolated from the large volumes of ascitic fluid usually present in ovarian cancer. Further studies of ascitic fluid may thus provide data on the nature of the immune responses in these patients.