Detection of immune complexes in systemic sclerosis and Raynaud's phenomenon

Phagocytosed immune complexes in polymorphonuclear leukocytes of nineteen patients with Raynaud's phenomenon were detected by scoring the cells for IgG and C3 inclusions. Parallel estimations of circulating immune complexes were made by liquid phase C1q binding and polyethylene glycol (PEG) precipitation methods. The results were compared with the degree of cold stress-induced vasospasm measured by quantified infra-red thermography. Thirteen of nineteen patients with Raynaud's phenomenon compared with only one of seventeen normal controls showed significantly elevated levels of phagocytosed IgG. The correlation of IgG and C3 scores for individual patients was high and the IgG and C3 scores correlated well with the thermographic assessment of the severity of the Raynaud's phenomenon. Two of the patients had elevated levels of circulating immune complexes detectable by raised levels of C1q binding, four patients had raised IgG and three patients raised IgM complexes detectable by PEG precipitation. None of the controls had elevated levels of circulating immune complexes detectable by either method. There was no correlation between the levels of circulating and phagocytosed immune complexes.