Figure 2. The roles of maternal MC cells on fetal immunity. The presence of maternal MC cells in the fetus can skew fetal immunity toward auto-reactivity. In normal human pregnancy, Mold et al.¹⁴ showed that fetuses developed Tregs specific for allo-antigens presented in utero in the presence of TGF-β leading to tolerance to the same allo-antigens later in life. Maternal MC T cells, strongly alloreactive toward any fetal antigen may produce inflammatory cytokines that would modify the tolerogenic environment via TGF-β which is critical for Treg development. Thus, it could be postulated that chronic persistence of fetal autoreactive T cells would escape the appropriate suppression by Tregs, consequently leading to autoimmunity.