Distribution of retroviral p15E-related proteins in neoplastic and non-neoplastic human tissues, and their role in the regulation of the immune response.

In patients with head and neck carcinomas and in patients with chronic purulent upper airway infections, low molecular weight retroviral p15E-like factors are found. These factors are responsible for partial defects in the cellular immune response. We studied the distribution of these p15E-related proteins in neoplastic, inflamed and normal human tissues and related these findings with the presence of p15E-like factors in patients' sera. Demonstration of p15E-like proteins in sera of patients with upper airway infections and of patients with head and neck carcinomas correlated exclusively with the presence of p15E in normal and pathologic epithelium of the upper respiratory tract. p15E was not demonstrated in epithelia of other localizations. Our results suggest that chronic stimulation or neoplastic transformation of the epithelia of the upper respiratory tract stimulates the production of p15E-like proteins leading to their reported immunosuppressive actions.