Abbreviations: 2′-FL, 2′-fucosyllactose; 3′-FL, 3′-fucosyllactose; 3′-SL, 3′-sialyllactose; 6′-SL, 6′-sialyllactose; BF, breast-fed; FF, formula-fed; HMO, human milk oligosaccharides; IFN-γ, interferon-γ; IHMO, isolated human milk oligosaccharides; LNFPIII, lacto-N-fucopentaose III; LNnT, lacto-N-neotetraose; LPS, lipopolysaccharides; PBMC, peripheral blood mononuclear cells; PHA, phytohaemagglutinin; SA, sialic acid; SLeX, sialyl-Lewis X; SR, sow-reared; TriGal, galactotriose