“…Adverse reactions to injections of y-globuUn preparations have mostly been presumed to be due to the presence of complement-activating IgG aggregates (5, 8,9,13,16,17,21,26). In addition, IgA deficiency and concomitant antibody formation against IgA have been clearly associated with reactions following infusion of blood products (18,22,25,33,(3)(4) or injection of y-globuIin preparations (1,25,28,34). IgA deficienq-and the presence of class-specific anti-IgA seem to accompany the most severe reactions (6, 24, 25, 28, 33, 34), but reactions also occur in patients with low levels of IgA and antibody of allotype specificity (33, 34).…”