CD4 and tuberculosis: However, our results demonstrate no evidence of reduced FcRn expression in any of the TB models compared to TF, and in fact suggest the percent of cells positive for FcRn expression is increased in multiple cell types (B Cells, CD4+ T Cells, NKCs, Mac/Mon, MDSCs) in splenocytes of LLC TB mice and in Mac/Mon of MC38 TB mice (Figure 4A).