PTPRC and influenza: To examine the localization of lung γδ T cells within distinct anatomical niches, namely the vasculature, airway and interstitial spaces, we i.v. injected fluorescein isothiocyanate (FITC)-labeled mAb against CD45 into mock- or influenza-infected mice and assessed its binding to γδ T cells as a criterion to discriminate circulating cells from parenchyma-bound cells.