Temperature-sensitive binding of solid phase C1q to aggregated human immunoglobulin G

The first component of complement (C1q) coupled to Sepharose by cyanogen bromide was found not to bind aggregated human γ-globulin or immune complexes at room temperature, whereas at 4°C binding was nearly complete. The temperature sensitivity of solid phase C1q binding was reversible. Elution of aggregated human γ-globulin bound at 4°C was possible by raising the temperature to 23°C. However, free C1q or C1q adsorbed onto polystyrene balls could bind immune complex-like material at both 23 and 4°C. The conformational restraints of C1q covalently coupled to a solid support may not allow functional activity at elevated temperatures.