Immune complexes in normal subjects

Immune complex (IC) levels were measured in normal subjects using the C1q solid phase, C1q deviation, C1q binding and polyethylene glycol precipitation assays. Significant changes in IC levels were seen in normals with each of the assays but the pattern of variation was not consistent between assays or subjects or in the same subject from day-to-day. There were no consistent changes with meals, time of day, exercise or the prior administration of prednisone. Low levels of IC appear to be normal in plasma but the variation in IC levels is not explained. Normal IC may well comprise mixtures of non-specific immunoglobulin aggregates, rheumatoid factor-immunoglobulin complexes, idiotype-anti-idiotype complexes as well as specific antibody complexes with antigens from food, infective agents and other sources.