Interleukin-18 serum level before and after intralesional immunotherapy with tuberculin purified protein derivative in patients with cutaneous and genital warts.

BACKGROUND

Several studies demonstrated the efficacy of intralesional purified protein derivative (PPD) immunotherapy in warts eradication. Nevertheless, the precise induced immune mechanisms are undetermined. Injected PPD is hypothesized to induce a delayed hypersensitivity reaction associated with cytokines release. Interleukin (IL)-18 has a major role in defense against viral infection via inducing interferon-γ release from T-helper 1 and natural killer (NK) cells. Moreover, IL-18 triggers Fas ligand expression on cytotoxic T cells and NK cells enhancing their cytotoxicity against virally infected cells.

AIM

The aim of this study was to assess the role of IL-18 in the response to intralesional PPD injection in patients with warts.

METHODS

The study included 25 patients with warts and 25 HCs. Patients underwent PPD skin test, and only patients with positive tests were included and received intralesional PPD injections starting 72 h after the test then every 2 weeks until wart clearance or a maximum of 3 sessions. Serum IL-18 level was measured via enzyme-linked immune-sorbent assay in patients (pre-treatment and 2 weeks after the last injection) and HCs.

RESULTS

After 3 sessions of injection, six (24%) patients were designated responders, nine (36%) patients showed partial response, and 10 (40%) patients were designated non-responders. Serum IL-18 level, post-treatment, was significantly higher than pre-treatment level (p = 0.025) and level in HCs (p = 0.036). Furthermore, the post-treatment level was significantly higher in responders than non-responders (p = 0.025).

CONCLUSION

IL-18 is probably implicated in the immune mechanisms induced by PPD injection that cause eradication of warts.