Exposure to radiation may have disastrous consequences for the body and its components. However, low-dose alpha radiation - as utilized in radon therapy - can exert beneficial biological effects and lead to improvement of the general health status and alleviation of symptoms in patients who suffer from diseases of autoimmune origin. In this context alpha radiation is believed to positively affect the immune system, leading to active anti-inflammatory immune reactions and regeneration of impaired body functions. This book summarizes the results of a study about the impact of alpha particle irradiation on the immune system of the skin. The findings obtained from the study support the theory that the immune system is involved in responses to alpha radiation in the skin, and contribute to the current understanding of radiation-dependent immune modulation, especially in the context of alpha particle-mediated treatments such as radon therapy. This book is aimed at students, scientists and medical health professionals, but also at patients who wish to get deeper insights in the current research in the fields of radiation biology and immune modulation by alpha particle-based therapy forms.