Objective: The negative effects on cheese quality of milk contaminated by spores of Clostridium butyricum and Cl.tyrobutyricum is prevented by the use of egg white lysozyme as additive. Since the presence of lysozyme in cheese could be possibly risky in allergic subjects, we aimed at investigating its absorption as well as serum IgE antibody titers after ingestion of Grana Padano cheese, an Italian DPO, long-ripened hard cheese, in white egg allergic subjects.
Methods: Cheese lysozyme was measured by HPLC. Ten healthy volunteers and 20 patients with hen egg hypersensitivity, RAST positive (binding > or = 3%) to lysozyme and/or ovomucoid and ovalbumin received 15, 30 and 60 g of cheese at distance of at least 2 weeks each. Serum lysozyme was measured by ELISA and specific IgE binding to lysozyme by the radioallergosorbent test (RAST).
Results: The concentration of lysozyme in cheese was 155 +/- 5 mg/kg. The area-under-the-curve of serum lysozyme after 15 g of cheese was 244.5 +/- 14.0 in controls and 330.2 +/- 9.9 in patients (p < 0.01). Similar results were obtained with 30 and 60 g of cheese. Only 3 patients (15%) showed positive IgE antibody responses to cheese (overall RAST mean 4.45 +/- 1.25 % vs. 4.24 +/- 1.02 % baseline, p = ns).
Conclusions: The amount of lysozyme absorbed with cheese was globally very low, although it was significantly lower in healthy controls than in allergic patients, where it induced an increase of IgE RAST score in 15% of subjects, without any clinical reaction. Therefore, the use of lysozyme as additive in Grana Padano cheese, does not appear to be harmful in egg allergic subjects.