Near-infrared 1064 nm laser modulates migratory dendritic cells to adjuvant the immune response to intradermal influenza vaccine

摘要

Brief exposure of skin to near-infrared (NIR) laser light has been shown to augment the immune response to intradermal vaccination and thus act as an immunologic adjuvant. Although evidence indicates that the NIR laser adjuvant has capacity to activate innate subsets including dendritic cells (DCs) in skin as conventional adjuvants do, the precise immunological mechanism by which the NIR laser adjuvant acts is largely unknown.Here we sought to identify the cellular target of the NIR laser adjuvant by using an established mouse model of intradermal influenza vaccination and examining the alteration of responses resulting from genetic ablation of specific DC populations. We found that a continuous wave (CW) NIR laser adjuvant broadly modulates migratory DC populations, specifically increasing and activating the Lang⁺ and CD11b⁻Lang⁻ subsets in skin, and that the antibody responses augmented by the CW NIR laser are dependent on DC subsets expressing CCR2 and Langerin. In comparison, a pulsed wave (PW) NIR laser adjuvant showed limited effects on the migratory DC subsets. Our vaccination study demonstrated that the efficacy of CW NIR laser is significantly better than that of PW laser, indicating that the CW NIR laser offers a desirable immunostimulatory microenvironment for migratory DCs.These results demonstrate the unique ability of the NIR laser adjuvant to selectively target specific migratory DC populations in skin depending on its parameters, and highlight the importance of optimization of laser parameters for desirable immune protection induced by a NIR laser-adjuvanted vaccine.