2001;108:1033C4. venom allergy (n=241), non-meat food allergy (n=222), and miscellaneous disorders (n=290). ImmunoCap was positive to alpha-Gal in 20/24 meat allergics and in 20/22 with positive gelatin skin tests. The results of gelatin skin screening and anti-alpha-Gal IgE were strongly correlated (r=0.46; P 0.01). Alpha-Gal was detected in bovine gelatin colloids at concentrations of ~ 0.44 to 0.52ug/gm gelatin by inhibition radioimmunoassay. Conclusion Most patients allergic to reddish meat were sensitized to gelatin and a subset was clinically allergic to both. The detection of alpha-Gal in gelatin and correlation between the results of alpha-Gal and gelatin screening raises the possibility that alpha-Gal IgE may be the target of reactivity to gelatin. The pathogenic relationship between tick bites and sensitization to reddish meat, alpha-Gal and gelatin (with or without clinical reactivity) remains uncertain. value 0.05 was considered statistically significance. Statistical analyses were performed with SPSS software, version 18.0 (SPSS, Inc, Chicago, Ill), and GraphPad Prism, version 4 (GraphPad Software, Inc, La Jolla, Calif). RESULTS Patient characteristics Between 1995 and 2011, 1159 adults assessed by the first author (RJM) aged 18 to 101 years (423 male) were diagnosed with FA, brought on by seafood (n=284 patients), peanut (n=189), tree nuts (n=188), systemic allergic reactions to fruit/vegetables (n=134), wheat (n=77), egg (n=57), reddish meat (n=40), sesame seed (n=22), cow’s milk (n=21) or soybean (n=8). Of 40 reddish meat allergics recognized, 18 (46%) were male aged 18-78 years (median 48) and 27 experienced anaphylaxis. Patients estimated symptom onset between 15 minutes and 9 hours after ingestion (median WEHI539 3 hours) with significantly delayed onset associated with nocturnal episodes after the evening WEHI539 meal. Ten were sensitized to reddish meat only (M) and 30 to reddish meat and gelatin (MG) on allergy screening. There was no relationship between onset time and likelihood of anaphylaxis (P=0.88) or gelatin sensitization and likelihood of anaphylaxis (P=0.13). With the exception of two vegetarians (MG1, MG26), most patients diagnosed with reddish meat allergy reported tolerance on other occasions. Meat and gelatin co-sensitization and co-reactivity 32 patients were co-sensitized to red WEHI539 meat and gelatin, including two patients with intraoperative gelatin colloid anaphylaxis who were red meat tolerant (GC 1 and 2) and 29 patients diagnosed with red meat allergy (MG 1-29; Table 1). Of this MG group, 12 reported anaphylaxis when red meat was not ingested, including two additional patients with intraoperative gelatin colloid anaphylaxis prior to presentation with red meat allergy (MG22 and MG24; 5). One additional patient (MG12) with recurrent red meat anaphylaxis remained well for five years on a meat/gelatin-free diet. Despite wearing a MedicAlert bracelet to warn of her possible gelatin allergy, she was given 40ml of intravenous Gelosfusine (~1.6gm gelatin) following a myocardial infarction and developed. urticaria, bronchospasm, hypoxia and hypotension (hospital records verified by the first author, RJM; Table 1). Nine additional patients reported systemic reactions following oral gelatin consumption on separate occasions (e.g. desserts) where meat ingestion was denied. Table 1 Clinical characteristics of patients diagnosed with red meat or gelatin allergy and other patient groups, as assessed by skin testing gelatin sensitization to be cautious about ingesting substantial quantities and to wear a MedicAlert bracelet warning of potential risk from gelatin colloid exposure, a prudent approach that did not protect one patient in our series. Consistent with previous studies (19, 30), in Rabbit Polyclonal to AKAP1 vitro testing appeared to be more sensitive at detecting sensitization to meat derived allergen than skin testing, with wheal sizes using commercial meat extracts being relatively small or negative and requiring IDT to detect sensitization (Table 1). Explanations for this have been discussed previously (19), including the possibility that folding of proteins within extracts might make alpha-Gal WEHI539 less available for mast cell cross-linking, that antibodies to uncharged carbohydrate molecules like alpha-Gal might be of low affinity (42), or perhaps of specific relevance, evidence that alpha-Gal concentration is lower in commercial meat extracts than in crude extracts of real meat (19), perhaps accounting for lower sensitivity. In this context, it is perhaps not surprising that IDT was more sensitive at detecting gelatin sensitization yet paradoxically in vitro testing was negative in almost all samples. This cannot be explained by serum sample degradation due to prolonged storage, since IgE to meat and alpha-Gal WEHI539 was detected in parallel assays. Potential explanations include assay insensitivity due to the preparation of gelatin required for immunoassay grade stability or if alpha-Gal is the allergenic target, insufficient concentration on the ImmunoCap to detect sensitization. Alternatively, gelatin-reactive IgE may be of low affinity or low concentration.