Pro-inflammatory cytokines, particularly interferon (INF)-γ, drive increased expression of IP collapse indicators (MHC class I and class II; β2-microglobulin) and down-regulation of locally generated key immunosuppressants (CD200 and TGFβ2) indicating collapse of the physiological HF IP; thereby exposing (usually hidden) HF antigens to immune surveillance [24]. The gene discussed is CD200; the disease is hydrops fetalis.