Successful desensitization of a patient with aplastic anemia to antithymocyte globulin.

Antithymocyte globulin (ATG) is a polyclonal gamma immunoglobulin derived from either rabbit or equine serum that serves as therapy for aplastic anemia; however, ATG causes serum sickness in up to 70% and anaphylaxis in up to 5% of recipients. Intradermal (ID) skin testing has been the primary technique used to evaluate for a preexisting Gell and Coombs type I hypersensitivity reaction to ATG. There are no data reporting the predictive value of delayed reactions to ID testing on the risk of serum sickness. This study was designed to establish the importance of epicutaneous and ID skin testing before the administration of ATG through a case report and literature discussion. We report a patient with severe aplastic anemia that was successfully desensitized to ATG after a negative epicutaneous skin test and positive ID skin test. The patient had neither systemic nor localized reactions during the desensitization. Desensitization to ATG in patients with positive epicutaneous skin testing has been shown to be associated with serious and potentially life-threatening complications and should only be considered when the benefits outweigh the risks. Epicutaneous skin testing should be considered in conjunction with ID skin testing when screening for potential sensitivity to ATG. Because of the serious risk of anaphylaxis, desensitization should be performed in an intensive care unit setting in conjunction with a physician familiar with drug desensitization and the management of anaphylaxis.

Successful administration of a 1-day imported fire ant rush immunotherapy protocol.

BACKGROUND: Young children with a history of systemic reactions to imported fire ant (IFA) stings are at substantial risk of recurrent stings because of their maturational inability to practice appropriate avoidance techniques. OBJECTIVE: To present 3 cases in which patients 36 months or younger completed a 1-day rush immunotherapy (RIT) protocol with IFA whole-body extract (WBE). METHODS: The 1-day RIT protocol used for these patients was modified from the Wilford Hall 2-day rush protocol previously published. A 1:1 vol/vol maintenance vial consisted of 1 mL of IFA WBE and 9 mL of human serum albumin diluent in a 10-mL vial. RESULTS: All 3 patients had positive intradermal skin test results to IFA WBE. No systemic reactions occurred during the 1-day RIT. CONCLUSIONS: This case series provides data with which we can begin to assess the efficacy and safety of a 1-day IFA RIT protocol for the prevention of anaphylaxis in IFA allergic children. Further studies with larger numbers of patients are needed to confirm the findings.

Effect of imported fire ant extract on the degradation of mountain cedar pollen allergen.

BACKGROUND: Dust mite, cockroach, and mold extracts have been shown to contain proteases capable of degrading the proteins in other extracts. Loss of potency of allergens has been reported in mixtures containing cockroach and fungal extracts. Fire ant venoms consist of 90% to 95% n-alkyl and n-alkenyl piperidine alkaloids, which are not allergenic. No studies are available addressing the mixture of imported fire ant (IFA) whole-body extract with other allergens or the presence of proteolytic activity in the venom extract. OBJECTIVES: To evaluate the stability of mountain cedar pollen extract mixed with IFA whole-body extract and to qualitatively analyze the extract mixture for degradation of mountain cedar protein. METHODS: One milliliter each of mountain cedar and IFA whole-body extracts at a concentration of 500 microg/mL were combined and stored at 4 degrees C for 1, 3, 6, 15, 30, 60, 90, and 180 days. Separate mixtures of 1 mL of mountain cedar and IFA with 1 mL of human serum albumin were used as controls. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed, and protein bands were qualitatively analyzed for degradation. RESULTS: We detected 3 distinct IFA protein bands and 1 mountain cedar protein band. With respect to these bands, no protein degradation was observed during 6 months of study in the extract mixture compared with the controls. CONCLUSIONS: Imported fire ant whole-body extract does not seem to degrade mountain cedar protein. Mixtures of allergenic extracts may be able to include IFA whole-body extract.