INTRAVENOUS IMMUNOGLOBULIN PREPARATION INCREASES MYOPLASMIC CALCIUM-CONCENTRATION BY ACTIVATING THE DIHYDROPYRIDINE-RYANODINE RECEPTOR COMPLEX

A human intravenous immunoglobulin preparation (IVIg) released Ca2+ fr om the sarcoplasmic reticulum of cultured human skeletal muscle cells in a dose-dependent manner. Blocking the dihydropyridine-ryanodine rec eptor complex abrogated the IVIg-mediated Ca2+ response, whereas inhib ition of the voltage-operated Na+-channels or acetylcholine receptors did not. This effect of IVIg was not mediated by its main component, t he IgG molecules, and differed between preparations from different man ufacturers. Heating destroyed the activity. Data shows that an unident ified serum protein present in IVIg can influence human muscle cells b y an effect on the dihydropyridine receptor. This phenomenon may be im portant in interpreting the (side) effects of IVIg in neuromuscular di seases. (C) 1998 Elsevier Science B.V.