HIV-1 INFECTION: Breast milk and HIV-1 transmission

Abstract

Leukocyte numbers, lactoferrin and IgA levels, and lymphocyte mitogenic activity in breast milk fall greatly to almost 0 during the first 2-3 months postpartum, but lactoferrin and IgA levels rise during the 3rd-12th month postpartum. Regardless of mother's HIV-1 status, breast-fed infants suffer fewer episodes of gastrointestinal and respiratory illnesses than do bottle-fed infants. Breast-fed, HIV-1 infected infants experience a longer median incubation period than do bottle-fed infants (19 vs. 9.7 months). The progression to AIDS in breast-fed infants is slower than in bottle-fed infants. The risk of HIV-1 transmission from a mother infected after delivery is 29% while it is 14% from a mother infected before delivery, suggesting that antibodies acquired transplacentally or through breast milk protect against HIV-1 infection in infants. Breast milk samples from 15 HIV-1 infected mothers reveal IgG and IgA antibodies against envelope glycoproteins and IgA antibodies against core antigens. A human milk factor blocks binding of HIV-1 to the CD4 receptor. A report in this issue of The Lancet shows HIV-1 specific IgM and IgA in 15-day postpartum breast milk, regardless of mother's immune status. There is a linear relationship between the persistence of these antibodies and the absence of HIV-1 infection in the infants. The authors believe neutralizing or cytotoxic activity protects infants against HIV-1 infection. More needs to be learned about mucosal transmission. If a cell-associated virus is responsible for HIV-1 infection, then the colostrum would be more infectious. Perhaps HIV-1 transmission could be reduced if mothers express and discard the colostrum and the early milk. This would be important to know, especially for women in developing countries. Further research is needed to learn how and when perinatal HIV-1 transmission occurs. In the interim, in areas where a safe alternative to breast milk exists, HIV-1 infected mothers should not breast feed.