Classification of Laser Vaccine Adjuvants.

An immunologic adjuvant, which enhances the magnitude and quality of immune responses to vaccine antigens, has become an essential part of modern vaccine practice. Chemicals and biologicals have been typically used for this purpose, but there are an increasing number of studies that are being conducted on the vaccine adjuvant effect of laser light on the skin. Currently, four different types or classes of laser devices have been shown to systemically enhance immune responses to intradermal vaccination: ultra-short pulsed lasers, non-pulsed lasers, non-ablative fractional lasers and ablative fractional lasers. Aside from involving the application of laser light to the skin in a manner that minimizes discomfort and damage, each type of laser vaccine adjuvant involves emission parameters, modes of action and immunologic adjuvant effects that are quite distinct from each other. This review provides a summary of the four major classes of "laser vaccine adjuvant" and clarifies and resolves their characteristics as immunologic adjuvants. These aspects of each adjuvant's properties will ultimately help define which laser would be most efficacious in delivering a specific clinical benefit with a specific vaccine.