Meat allergy: I - Specific IgE to BSA and OSA in atopic, beef sensitive children

Objective: The use of lamb meat products has been suggested as an alternative diet for polyallergic children, although until now this clinical practice has not been supported by in-depth biochemical/immunological studies. The aims of this research were: to evaluate cross-reactivity between lamb and beef; to evaluate the role of BSA and OSA as allergens in beef allergic children; and to evaluate cross-reactivity between BSA and OSA. Methods: 16 children suffering from atopic dermatitis (AD), aged 12 months-8 years (mean age 2.61 ± 1.93 years) were found skin prick test (SPT) - positive to bovine meat; all of them were also SPT-positive to ovine meat and to milk. After a period of restricted diet, the selected 16 children were recalled; 12 AD-free children (8 males and 14 females, aged 12 months-4.33 years (mean age 2.21 ± 1.05 years) were evaluated by SPT and radioallergosorbent test (RAST) for the following allergens: bovine meat, ovine meat, BSA 1 mg/ml, OSA 1 mg/ml. Double-blind, placebo-controlled food challenge (DBPCFC) with bovine serum albumin (BSA) and ovine serum albumin (OSA) were performed. For SPT, the results were expressed in mm of wheal, and 3 mm was considered as the end point; correlation between wheal diameters was calculated by Spearman rank test. For DBPCFC, according to the Sampson's experimental procedure, BSA and OSA were given in pear juice (the dermal negative response to the pear juice was verified by fresh food SPT before starting the oral challenge test). The total dose administered to the children corresponded to the amount of albumin present in 180 g of calf or lamb meat (90 and 63 mg respectively, as calculated by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SPS-PAGE). The administration of pear juice (containing placebo or albumin) and symptom evaluation were entrusted to medical people who did not know what the child received. Results: All children tested SPT positive to bovine and ovine meat, and to BSA and OSA. Significant correlations were observed between the following diameters of wheal: BSA vs OSA (R = 0.846, p < 0.0001); ovine meat vs OSA (R = 0.769, p < 0.005); b.meat vs o.meat (R = 0.771, p < 0.005); and ovine meat vs BSA (R = 0.594, p < 0.043). In RAST, 6 of 12 children were positive to bovine meat, 3 to lamb meat, 4 to BSA and 3 to OSA. DBPCFC showed an immediate reaction to BSA or OSA in 2 and 3 children, respectively. One other child developed severe dyspnea, cough and asthma 3 hours after OSA challenge. Conclusions: BSA and OSA are important beef and lamb allergens; they share not only protein sequences, but also allergenic properties. Clinical tolerance to BSA and OSA can be present in beef and lamb SPT-positive children.