SULFONAMIDE-INDUCED REACTIONS IN DESENSITIZED PATIENTS WITH AIDS - THE ROLE OF COVALENT PROTEIN HAPTENATION BY SULFAMETHOXAZOLE

Background: Adverse reactions to sulfonamides cause significant morbid ity in patients with AIDS. We have demonstrated previously a similar o r equal to 40 kd sulfamethoxazole (SMX)-substituted protein in the ser um of some individuals treated with SMX. Objective: The purpose of thi s study was to examine patients with AIDS who had undergone SMX desens itization because of a prior history of SMX allergy for the presence o f SMX-haptenated serum proteins and to determine whether these protein s, SMX-specific Ige antibodies, or both predict the development of sub sequent clinical reactivity. Methods: Four patients with no history of allergy and in whom SMX prophylaxis was initiated and eight patients with AIDS who had undergone SMX desensitization because of prior aller gy were evaluated. SMX-conjugated serum proteins mere identified with an immunoblotting assay, and SMX-specific IgG antibodies were identifi ed by ELISA inhibition. Results: One of the four patients receiving SM X prophylactic treatment demonstrated SMX-protein haptenation, none ha d detectable SMX-specific IgG antibodies, and none developed an SMX-as sociated reaction during the time in which they were followed. Of the eight patients who underwent SMX desensitization, six (75%) demonstrat ed SMX-protein haptenation, and three of these six (50%) subsequently developed SMX-induced cutaneous reactions. Only one of these six patie nts had detectable SMX-specific IgG antibodies. The two individuals wh o did not demonstrate SMX-protein haptenation have not developed a cli nical reaction. Conclusion: These preliminary data suggest that SMX ha ptenation, but not SMX-specific antibodies, mag be important in the de velopment of clinical sensitivity in patients with AIDS who have under gone SMX desensitization.