Effect of immunization against rubella on lactation products. I. Development and characterization of specific immunologic reactivity in breast milk.

The development of an immune response to rubella virus in milk, serum, and nasopharyngeal secretions was studied in lactating postpartum women after immunization with HPV-77 De5 or RA 27/3 live, attenuated rubella virus vaccine administered subcutaneously or intranasally. Over 69% of the women shed virus in milk after immunization. A predictable nasopharyngeal IgA and serum IgG antibody response to rubella virus was observed after subcutaneous or intranasal immunization with RA 27/3 vaccine. Little or no nasopharyngeal antibody response was seen after subcutaneous immunization with HPV-77 DE5 vaccine. A virus-specific IgA antibody response in milk was seen in all women. The presence of rubella virus in breast milk seemed to potentiate the peak levels of virus-specific antibody in the milk. Cellular immune reactivity to rubella virus in milk was observed in all vaccine groups. Thus, the virus-specific immune response induced in human milk after immunization with rubella virus vaccine may be intimately linked with the reactivity in bronchial lymphoid tissue.