Cummings and Smith are pioneers in the field of glycomics, studying the sugar molecules that decorate our proteins and coat our cells. They have found that human milk contains specialized glycans (carbohydrate linked to other molecules such as protein or lipid) that bind to influenza virus. This is separate from, and a supplement to, the adaptive immunity of antibodies and vaccines.
“The anti-flu glycans are not induced to our knowledge, but are part of a naturally occurring ‘liquid innate immune system’ in human milk,” Cummings says. “We’re very excited about this, and the availability of the human milk glycome in printed microarray formats will now allow screening for glycan binding to a wide variety of infant pathogens. This came from a single donor, so as to not complicate the matter yet, but work in progress shows that glycans from other donors have many related but also different glycans.”
He adds that his lab is finding that the glycans in human milk are different overall in complexity and makeup from those in other mammals.
Smith hypothesizes that the glycans may be functioning as “decoy receptors,” interfering with the molecules on the surfaces of human cells that viruses use to gain access.