[Radioimmunologic detection of IgE and IgG antibodies against drugs. Conclusions after experience with over 1200 patients].

Based on the radioallergosorbent test (RAST), the authors have developed a series of assays to detect IgE and IgG antibodies against a number of frequently used drugs. In this system drugs bound covalently to cellulose paper are incubated with serum and washed; the hapten-specific IgE and IgG antibodies are then qualified and quantified by means of 125I-labelled anti-human IgE and IgG respectively. Thus far the sera of 1,228 patients have been analyzed following therapy with betalactam antibiotics, co-trimoxazole, salicylates, pyrazolones, flavonoids and tetrahydroisoquinoline. The induction of IgG antibodies is a frequent occurrence and that of IgE rare. Isolated high titers of IgE are associated mainly with anaphylactic reactions; in the presence of simultaneously raised IgG titers such side reactions are often absent. Highest IgG titers were found in patients with immune hemolysis after betalactam antibiotics, flavonoids and tetrahydroisoquinoline. In the other types of side reaction specific IgG titers were not significantly higher than in patients without side reactions. The estimation of circulating antibodies against drugs cannot yet be utilized diagnostically except in the rare cases of anaphylactic side reactions. However, the method described permits specific and sensitive detection of sensitization and is suited for scientific purposes.