Prospective evaluation of chymopapain sensitivity in patients undergoing chemonucleolysis.

Immediate anaphylactic reactions after intradiscal chymopapain (CP) injection may occur in 1% of patients undergoing chemonucleolysis (CN). Skin prick testing to CP (10 mg/ml), a prescreening history, and CP serum-specific IgE determinations by the RAST method were performed in order to identify patients presensitized to CP before CN. Follow-up repeat CP skin testing and serum-specific IgE were done 2 to 6 weeks after CN to detect CP IgE-mediated sensitization resulting from the injection. Three of 84 patients who exhibited positive skin tests to CP before CN did not receive CP injections. Only one of the three patients (33%) was detected with elevated CP serum-specific IgE before CN. No immediate severe anaphylactic reactions caused by CP injection were encountered in the remaining 81 patients with negative CP skin tests and RASTs before CN. Eight (10%) nonlife-threatening immediate and late reactions were associated with conversion from negative skin tests and RASTs before CN to positive skin tests or RASTs after CN. Overall, 19 of 52 (37%) patients who returned for follow-up testing developed cutaneous sensitization to CP after CN. Despite the fact that RAST values after CN in these patients were significantly higher (p less than 0.002) than those with negative skin tests after CN, the sensitivity of the RAST was only 72% for identifying patients who developed positive CP skin tests after CN. This study demonstrated that CP skin testing is essential for prescreening patients because it was more sensitive than RAST for identification of CP sensitivity both before and after CN. Late allergic reactions and cutaneous sensitization to CP were common sequelae of CN.