Local production of antibody by the lactating mammary gland following antigenic stimulation.

Abstract

SummaryExperiments have been carried out to determine whether the infusion of antigens into the dry mammary glands of pregnant ewes gives rise to a sustained local immunity. One side of the udder was infused with killed Salmonella typhi “O” organisms and the other with a similar dose of killed Brucella abortus organisms. Infusions were given to 6 pregnant ewes about 1 month before parturition.Although the anti‐Salmonella and anti‐Brucella titres in the colostrum from both sides were higher than those in plasma, the titres of specific antibody in colostrum from the sides receiving corresponding specific antigen were usually higher than in the colostrum from the opposite side. These results indicated that both local synthesis and active transfer of antibody were occurring at this time.There was a rapid fall in the antibody titres of milk within the first week of lactation. However, the ratio of the titres of specific antibody in the samples from the sides receiving corresponding specific antigen to those in plasma were usually well above unity throughout lactation. On the other hand, the milk: plasma ratios computed from the anti‐Salmonella and anti‐Brucella titres in plasma and in whey samples collected from the sides which were not infused with corresponding antigens rapidly decreased within 2 weeks after parturition to values which varied between 0·03–0·25. These results indicated that during lactation most of the specific antibody in milk was of local origin.The anti‐Salmonella and anti‐Brucella titres in the mammary lymph from the sides infused with Salmonella and Brucella respectively were lower than those in the milk from the same side. In view of the relative impermeability of the glandular epithelium of the mammary gland to γ‐globulin molecules, this finding suggests that the cells responsible for local synthesis of antibody are in close proximity to the glandular epithelium.