The levels of IL-6 and IFN-γ in tear fluid in ocular GvHD patients were significantly elevated in comparison to patients without ocular GvHD and healthy controls (p<0.005 for each) The levels of IFN-γ correlated with the Schirmer score (r=-0.48, p<0.0001) and tear break up time (TBUT; r=-0.38, p=0.03). Here, IFNG is linked to graft versus host disease.