Human milk banking I. Effects of container upon immunologic factors in mature milk

Abstract

The effects of the type of storage container and the duration of storage upon the concentrations of lactoferrin, lysozyme, secretory IgA (SIgA), total IgA, and SIgA antibodies to E. coli somatic antigens and upon the numbers and functions of macrophages, neutrophils and lymphocytes in mature human milk were examined. Milk samples collected during the fourth week of lactation from women aged 20–35 years were kept in pyrex and polypropylene or polyethylene containers at 4°C for 4 and 24 hours. The concentrations of lactoferrin and lysozyme fell by 30% and 40%, respectively, after storage for 24 hours in pyrex and polypropylene containers. The concentration of SIgA antibodies to E. coli O antigens did not change with time in samples stored in pyrex or polypropylene containers but fell by 60% in samples stored in polyethylene. The numbers of macrophages and neutrophils were similar in all containers after 4 hours of storage but increased after 24 hours, particularly after storage in pyrex containers. A similar pattern was found in respect to the number of lymphocytes. The uptake of 3H-thymidine by phytohemagglutinin stimulated milk lymphocytes decreased significantly after 24 hours of storage. These findings indicate that the storage of mature milk at 4°C for comparatively brief periods induces significant changes in the concentrations and/or functions of key immunological components.