CD69 and cytomegalovirus infection: Importantly, these changes in phenotypic markers required both the presence of the BsAb in culture and HCMV infection, since elevated expression of CD25, CD69, and the degranulation marker CD107a was detected only in the presence of HCMV-infected ARPE-19 cells, not in uninfected ARPE-19 cells (Fig. 3D through F).