Immunosuppressive retroviral P15E-related factors in head and neck carcinomas.

We report on the effect of low molecular weight factors (LMWFs) derived from 14 different head and neck carcinomas on the chemotactic responsiveness of healthy donor monocytes, as measured by their polarization activity. The factors inhibited the polarization of the monocytes significantly (61.5% to 94.5% vs 12.5% to 29% in cases where the LMWF was derived from healthy oral mucosa). The inhibitory effect exerted by these LMWFs could be neutralized only by absorption with one of three different murine monoclonal antibodies or a rabbit polyclonal antibody to the murine retroviral envelope protein P15E. This shows that retroviral-related material is present in head and neck carcinomas and that this material is responsible for the observed defective polarization that probably underlies the earlier described defects on monocyte chemotactic responsiveness.