The exact mechanisms underlying the contribution of cellular immunity in the eradication of human papillomavirus (HPV) infections remain obscure. Individuals who have treatment-resistant warts frequently have immune deficiencies. Amino-peptidases (ERAP1, ERAP2) of endoplasmic reticulum are essential for production of antigenic epitopes that attach to the Major Histocompatibility Complex (MHC) class I and activate T-lymphocytes or natural killer (NK) cells. Aim: To assess ERAP1 and ERAP2 serum concentrations in patients with resistant warts.

Inclusion Criteria:

• Patients who had a history of incomplete clearance or recurrence following two or more electrocautery sessions and four or more cryocautery treatments and intralesional bleomycin.

Exclusion Criteria:

• Patients with genital warts
• Patients on systemic steroids or other immunosuppressive treatments
• Immunocompromised individuals
• Patients suffering from chronic systemic diseases
• Pregnant women

Two hundred individuals were separated into two groups. Group (I) patients with resistant warts (n=100), and group (II) age- and sex-matched subjects with history of treated warts with no recurrence (n=100). They were recruited from the Dermatology Outpatient Clinic at Benha University Hospitals