Wróblewska B., Kaliszewska A. (2012): Cow's milk proteins immunoreactivity and allergenicity in processed food. Czech J. Food Sci., 30: 211-219.The immunoreactivity and allergenicity of proteins present in processed food (UHT milk, yoghurt, hard cheese, cottage cheese, biscuit, and sausage intended for children) were determined in this study. Proteins were characterised by SDS-PAGE electrophoresis. The changes in immunoreactivity were compared by enzyme-linked immunosorbent assay (ELISA) using polyclonal rabbit antibodies specific to α-lactalbumin (α-la), β-lactoglobulin (β-lg), α-, β-, and κ-casein. The allergenicity was determined with human pooled sera from CMA allergic patients by ELISA and immunoblot. The results have shown that the allergenicity of the food products is mainly correlated with bovine serum albumin (BSA), lactofferin (LF), and α-casein or the products of non-specific reactions between carbohydrate and proteins (e.g. lactosylation).