Variation in circulating immune complex levels with diet, exercise, and sleep: a comparison between normal controls and patients with systemic lupus erythematosus.

Circulating immune complexes (CIC) were measured in 4 normal controls and 8 patients with systemic lupus erythematosus (SLE) by a polyethylene glycol precipitation (PEG) method during a 24-hour period. In all the normal controls levels fell during sleep and after drinking 1 pint (568 ml) of milk and rose before getting out of bed and after moderate exercise. There were also marked differences in the patterns of rise and fall of the CIC levels between the normal controls and patients with SLE. Insufficient account has been taken of these physiological influences in CIC levels in previous studies attempting to relate disease activity to quantitative levels.