CD4 and hydrops fetalis: As anticipated, IgG treated HF mice showed a 1.5-fold increase of the percentage of lung CD4+ Tem, a 16% decrease of the percentage of lung naïve T cells, and a 3.6-fold increase in the ratio of lung CD4+ Tem to naïve T cells as compared with the data of the sham group (Figures 3G–I).