In vitro complement consumption by contrast materials and analogues: reactors vs. nonreactors.

Blood samples from previous contrast reactors and nonreactor controls were incubated with diatrizoate and several contrast analogues. Total complement levels were assayed. All the agents caused complement activation generally proportional to their concentration. Reactors' sera responded to lower concentrations of contrast or analogues than did control sera. Such studies might be of value in predicting contrast reactors.