ALLERGIC CROSS-REACTIONS BETWEEN CAT AND PIG SERUM-ALBUMIN - STUDY ATTHE PROTEIN AND DNA LEVELS

After observing a patient allergic to cat dander and pork but devoid o f other allergies, we prospectively screened patients known to be alle rgic to cat for a second sensitization to pork. After collecting the s era of 10 young patients found to contain specific IgE to cat dander a nd pork, we undertook this study to detect the possible cross-reactive allergen, define its molecular characteristics, and evaluate its clin ical relevance. Through immunoblotting techniques, cat and porcine ser um albumin were found to be jointly recognized molecules. These findin gs were further analyzed by specific anti-albumin IgE titrations and c ross-inhibition experiments. Cat serum albumin cDNA was obtained from cat liver, and the corresponding amino acid sequence was deduced and c ompared to the known porcine and human serum albumin sequences. Inhibi tion experiments showed that the spectrum of IgE reactivity to cat ser um albumin completely contained IgE reactivity to porcine serum albumi n, suggesting that sensitization to cat was the primary event. In two cohorts of cat-allergic persons, the frequency of sensitization to cat serum albumin was found to lie between 14% and 23%. Sensitization to porcine albumin was found to lie between 3% and 10%. About 1/3 of thes e persons are likely to experience allergic symptoms in relation to po rk consumption. Sensitization to cat serum albumin should be considere d a useful marker of possible cross-sensitization not only to porcine serum albumin but also to other mammalian serum albumins.