Expression of programmed cell death ligand 1 and programmed cell death 1 in cutaneous warts

Wesley Y. Yu, Timothy G. Berger, Jeffrey P. North, Zoltan Laszik, Jarish N. Cohen

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Background: Cutaneous warts have high prevalence and cause significant morbidity. Understanding the mechanisms by which warts evade the immune system could lead to targeted and improved treatments. Objective: To determine whether cutaneous warts express programmed cell death ligand 1 (PD-L1) and to characterize the expression of programmed cell death 1 (PD-1) within the immune infiltrate of inflamed lesions. Methods: In total, 44 biopsies of cutaneous warts were retrieved from the Department of Dermatopathology archives of the University of California, San Francisco. Biopsies were stained with hematoxylin and eosin and PD-L1 monoclonal antibody, and biopsies of inflamed lesions were stained with PD-1 monoclonal antibody. Results: PD-L1 was expressed on keratinocytes in cases of verrucae vulgares (12/30, 40%) and myrmecia (7/14, 50%) and was associated with an interface inflammatory reaction. PD-1 was expressed by the inflammatory infiltrate in verrucae vulgares (21/24, 88%) and myrmecia (5/8, 63%). Limitations: This was a retrospective observational study conducted at a single institution. Conclusion: Many cutaneous warts express PD-L1, suggesting that human papillomavirus might use this pathway to promote immune dysfunction. This discovery helps explain the recalcitrance of warts to current therapies and provides a rationale for investigating anti–PD-1 immunotherapy as a potential treatment for warts.

Original languageEnglish (US)
Pages (from-to)1127-1133
Number of pages7
JournalJournal of the American Academy of Dermatology
Issue number5
StatePublished - Nov 2019
Externally publishedYes


  • HPV
  • PD-1
  • human papillomavirus
  • immunotherapy
  • interface dermatitis
  • pathophysiology
  • virology
  • warts

ASJC Scopus subject areas

  • Dermatology


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