Regression of canine oral papillomas is associated with infiltration of CD4+and CD8+lymphocytes

Canine oral papillomavirus (COPV) infection is used in vaccine development against mucosal papillomaviruses. The predictable, spontaneous regression o f the papillomas makes this an attractive system for analysis of cellular i mmunity. Immunohistochemical analysis of the timing and phenotype of immune cell infiltration revealed a marked influx of leukocytes during wart regre ssion, including abundant CD4(+) and CD8(+) cells, with CD4(+) cells being most numerous. Comparison of these findings, and those of immunohistochemis try using TCR alpha beta-, TCR gamma delta-, CD1a-, CD1c-, CD11a-, CD11b-, CD11c-, CD18-, CD21-, and CD49d-specific monoclonal antibodies, with previo usly published work in the human, ox, and rabbit models revealed important differences between these systems. Unlike bovine papillomavirus lesions, th ose of COPV do not have a significant gamma/delta T-cell infiltrate. Furthe rmore, COPV lesions had numerous CD4(+) cells, unlike cottontail rabbit pap illomavirus lesions. The lymphocyte infiltrate in the dog resembled that in human papillomavirus lesions, indicating that COPV is an appropriate model for human papillomavirus immunity. (C) 2001 Academic Press.