Immunological response in egg-sensitive adults challenged with cheese containing or not lysozyme

Objective Lysozyme is an enzyme that hydrolyzes bacterial peptidoglicans and for this reason is used in cheese manufacturing in order to prevent a defect of long-ripened hard cheese called “late blowing”, due to the outgrowth of spores of Cl. tyrobutyricum and Cl. butyricum. Moreover, germination of L. monocytogenes spores into vegetative cells is also sensitive to lysozyme. Lysozyme can be an allergenic molecule and for this reason there are concerns about its use in food industry. The immunological and clinical response of consumption of lysozyme containing cheese, has been evaluated in 25 egg-sensitive subjects with or without lysozyme sensitization. Methods Twenty-five egg-sensitive subjects were enrolled in this study. All the subjects were already treated for egg-sensitization and presented positive Skin Prick Test. All the subjects had a BMI ≤ 25 kg/m2 and were in the range of 20-50 years. Each subject was studied twice and received randomly 30 gr of Grana Padano (containing lysozyme) or TrentinGrana cheese (lysozyme-free) of two different aging periods: 16 or 24 months. A wash-out period of 1 week between each cheese intake was adopted. Blood samples were taken in fasting conditions and 1 hour after cheese intake and Ig A, total Ig E and lysozyme, ovomucoid and ovalbumin-specific Ig E measured. Results No adverse reactions were observed in both groups of patients after cheese samples were given. Lysozyme did not determine any variation of specific Ig E compared with basal level. In lysozyme sensitive patients a significant relationship between Ig A and lysozyme specific Ig E was observed when lysozyme-containing cheese was given, confirming that lysozyme can pass the gut barrier. Conclusions Neither adverse events nor immunological responses were observed after ingestion of cheese containing lysozyme. However, the immunological properties of peptides deriving from cheese protein hydrolysis need to be clarified as well as the effect of lysozyme on bacterial proteolytic activity.