Evaluation by enzyme-linked immunosorbent assay of local and systemic production of milk immunoglobulins to surface exopolysaccharide antigen in cows with staphylococcal mastitis

An enzyme-linked immunosorbent assay (ELISA) was developed to evaluate milk immunoglobulin levels to surface exopolysaccharide antigen of Staphylococcus aureus in cows with staphylococcal mastitis. Quarter milk samples were obtained from 24 lactating dairy cows on two occasions, one month apart. Cows were classified as S. aureus-positive (S. aureus cultured from at least one quarter on both sample dates) or S. aureus-negative. Individual quarter samples were tested for IgA (representing local synthesis) and IgG1 (primarily of systemic origin) specific for staphylococcal surface exopolysaccharide antigen. No significant differences were found for specific IgA or IgG1 between S. aureus-positive and S. aureus-negative cows, nor between infected and non-infected quarters of S. aureus-positive cows. The data indicate that, in cows with staphylococcal mastitis, milk immunoglobulins specific for exopolysaccharide antigen are not significantly increased by either the systemic or the local immune response.