CD274 and infection: For example, Groeger et al. [85] assessed the in vitro expression of B7-H1 and B7-DC receptors on squamous cell carcinoma cell lines SCC-25 and BHY and primary human gingival keratinocytes (PHGK) following infection with two virulent strains of P. gingivalis (W83 and ATCC 33277T).