Nutrition and HIV/AIDS: A Training Manual - Linkages Project

Up to 70 percent of breastmilk samples from HIV-infected mothers have been shownto contain cell-associated and cell-free HIV. Transmission is not necessarily a resultof the presence of HIV in breastmilk, however, but of a complex interaction betweenthe anti-infective agents—macrophages, lymphocytes, and immunoglobulin— inbreastmilk and HIV.Possible mechanisms of transmission through breastmilk (slide 13)One theory to explain the transmission of HIV through breastmilk is that M-cells—specialized epithelial cells that comprise only one percent of all epithelial mucosalcells found in the Peyer’s patches of intestinal mucosa—engulf the virus and allow itto pass through to the macrophages on the other side. The M-cells could facilitatepassage through the single layer of cells in the gut that are connected with mostlyimpermeable junctions (Featherstone 1997). Another study showed the HIV-infectedcells in the intestinal lumen stimulated enterocytes to engulf HIV particles (Bomsel1997). More research is needed in this area.Research conducted in Rwanda with 215 HIV-1-infected women examined how threefactors (HIV-1-infected cells, deficiencies in anti-infective substances in breastmilk,or both) influenced transmission at 15 days, 6 months, and 18 months post-partum(Van de Perre et al 1993). Immunoglobulin (Ig) G was the most frequently identifiedHIV-specific antibody in breastmilk, followed by immunoglobulin (Ig) M. Thestrongest predictor of transmission was HIV-1 infected cells in breastmilk andcombined with a defective IgM response.Anti-HIV activity in breastmilk (slide 14)Human lactoferrin, with demonstrated inhibitory effects on E. coli and otherpathogens, has been shown to ward off HIV (Harmsen et al 1995). Lipid-dependentantiviral activity against HIV and other enveloped viruses and bacteria has also beenidentified (Isaacs and Thormar 1990; Orloff et al 1993). A sulphated protein,glycoprotein mucin or glycosaminoglycan, also appears to inhibit the binding of HIVto CD4 receptors (Newburg et al 1992).Studies vary greatly on the presence of cell-free and cell-associated virus incolostrum. Some research (Ruff et al 1994; Van de Perre et al 1993) shows more HIV190