Serum levels of immunoglobulin and complement in giant-cell arteritis.

The levels of IgG, total complement, and complement factors C3 and C4 were elevated in serum from patients with giant-cell arteritis as compared to a control group of patients in the same range of age. No increase of the IgM concentration was found. The concentration of IgA was higher in men with giant-cell arteritis as compared to men in a control group. This increase of IgA was not seen in women. There were no statistically significant differences in any of the studied variables between those with a histologically verified arteritis on temporal biopsy specimens and those without.