Analysis of the presence of natural killer cell subpopulations in preterm human milk: A first approach

Abstract

Several immune cell populations are transferred to the newborn through breast milk, including natural killer (NK) cells, which are critical for innate defense and regulation of the immune response, especially in preterm infants. The aim of this study was to analyze the presence of NK cell subpopulations in different types of preterm breast milk. The study quantified the presence of NK cell subpopulations by flow cytometry using the relative expression of CD56 and CD16 markers in colostrum, transitional and mature milk samples from preterm mothers. Flow cytometry analysis revealed the presence of five NK cell subpopulations, but unlike those reported in peripheral blood, CD56^dimCD16⁺ and CD56^-CD16⁺ populations are predominantly present in preterm milk, only the CD56^brightCD16^dim population is increased in mature milk. Analysis of NK cell subpopulations in preterm milk revealed a pattern of NK cell presence in preterm breast milk with predominantly cytotoxic phenotypes in relation to CD16 marker expression.