The humoral and cell-mediated immune response to human papillomavirus type i (HPV-i) has been studied in 162 patients carrying papillomas of various clinical types: deep plantar wart or myrmecia, common wart, flat wart, and anogenital wart. Circulating antibodies were detected by immunodiffusion and microcomplement fixation, using purified HPV-i particles as type-specific antigen. A significant association between myrmecia and anti-HPV-i antibodies was found (39% of the cases).

Cell-mediated immunity was evaluated by a study of delayed hypersensitivity (DH). The main capsid components of HPV-i (HPV-i CP), consisting mostly of a polypeptide of molecular weight 54,000, were injected intradermally. In addition to the type-specific antigens, HPV-i CP contain other antigenic determinants shared by various types of human papillomaviruses and masked in intact viral particles. The DH tests to HPV-i CP showed no differences between the carriers of different papilloma types, confirming the presence of common antigenic determinants. Moreover, they gave rise to an increase or to new anti-HPV-i antibody production mostly in myrmecia carriers (78% and 33% of the cases, respectively), and to new DH to HPV-i CP in all groups of papilloma carriers (33% to 56%, depending on the clinical papilloma type).