PTPRC and influenza: We therefore examined cells expressing hyaluronan synthases and hyaluronidases by sorting CD45−EpCam+ epithelial cells, CD45−CD31+ endothelial cells, CD45−EpCam−CD31− ‘stromal’ cells such as fibroblasts, and CD45+ ‘immune’ cells (Fig. 2) from homogenised lung tissue after influenza infection.