<p>Human IgGs were detected in the serum of HF mice (A–B) and the milk/serum ratio was significant lower in HF transgenic mice (C–D). The milk/serum ratio is used as an index for the transfer of human IgGs from milk to serum in the mammary gland. The concentrations of murine IgGs (E–F) and the ratio of serum/milk (G–H) indicated that there was no transfer of murine IgGs by bFcRn. The ratio of serum/milk is used as an index for the transfer of murine IgGs from serum to milk. D3-serum, serum obtained on day 3 of lactation; C, colostrum collected on day 3 of lactation; D10-serum, serum obtained on day 10 of lactation; M, milk collected on day 10 of lactation. The data were combined from three independent experiments; the bars represent the means ± SD (n = 7–8 mice per group); <i>*P</i><0.05; <i>**P</i><0.01.</p
