Background: Natural killer (NK) cells are components of the innate immune defense system, and their levels differ between breast and formula-fed (FF) infants. Lactoferrin (Lf) modulates NK cell cytotoxicity ex vivo. We hypothesized that dietary bovine Lf (bLf) would increase NK cell populations and cytotoxicity.
Methods: Piglets were sow-reared (SR), FF, or 1 g/l bLf-fed (LF) for 21 d. NK cells (CD3(-)CD4(-)CD8(+)) in blood (peripheral blood mononuclear cells (PBMCs)), spleen, and mesenteric lymph node (MLN) were determined by flow cytometry. PBMC NK cells were tested for cytotoxic activity against target K562 cells ex vivo in the presence of media (unstimulated), interleukin-2, or bLf. NK cell mRNA expression was determined by reverse transcription-quantitative PCR.
Results: SR and LF piglets had more NK cells in MLN (P = 0.0097) and spleen (P = 0.0980) than FF piglets. In PBMCs, SR piglets had more NK cells than FF piglets (P = 0.0072); LF piglets were intermediate and not different from FF or SR piglets. NK cell intelectin-2 mRNA expression was 2.5-fold higher (P = 0.0095) in LF than SR or FF piglets. NK cells in SR piglets exhibited greater (P < 0.0001) cytotoxic activity than those in LF or FF piglets, which was supported by greater perforin mRNA expression.
Conclusion: Dietary bLf increased blood NK cell populations and NK Lf receptor expression but not NK cell cytotoxicity.