Effect of P15E related retroviral material isolated from head and neck carcinomas on delayed type hypersensitivity skin reactions in mice.

Low molecular weight factors, derived from head and neck carcinomas (H/N ca LMWFs), exert a serious inhibitory effect on monocyte chemotaxis both in vivo and in vitro. This effect can be neutralized by the treatment of the factors with three different monoclonal antibodies to P15E, one of the structural envelope proteins of murine leukemia virus (MuLV). In this study, we report the effect of the H/N ca LMWFs on the delayed type hypersensitivity responsiveness in mice: the factors significantly inhibited the 24 hour DNFB skin reaction. These effects of the H/N ca LMWFs were again neutralizable by antibodies to P15E. Additional experiments showed that the H/N ca LMWFs had equal suppressive effects on toxic skin reactions to croton oil, and this indicates that the P15E-like H/N ca LMWFs exert their effect by aspecific mechanisms.