The immune system, the skin, and childhood rheumatic disease.

As the body's largest organ and first line of defense against the environment, the skin plays a vital role in host immune defense. In addition to its function as a physical barrier, the skin contains an active immune surveillance network and can mount highly specific responses to eliminate invading organisms. In this review, we discuss the functions of adhesion molecules in regulating the recruitment of distinct cell populations to skin in both healthy and disease states, and the interaction between innate and adaptive immune mechanisms active in the skin. We also review how these systems underlie the pathogenesis of skin manifestations of pediatric rheumatologic diseases.