The most prevalent cancer diagnosed in the world is sunlight-induced skin cancer. In addition to being a complete carcinogen, UV radiation, the causative agent of skin cancer, induces immune suppression. Because UV-induced immune suppression is a well-recognized risk factor for skin cancer induction, it is crucial to understand the mechanisms underlying UV-induced immune suppression. Mast cells, which have recently emerged as immune regulatory cells, are particularly important in UV-induced immune suppression. UV exposure does not induce immune suppression in mast cell-deficient mice. We report that UV irradiation blocks germinal center (GC) formation, Ab secretion, and T follicular helper (Tfh) cell function, in part by altering the expression of transcription factors BCL-6 and BLIMP-1. No suppression of GC formation, Tfh cell IL-21 expression, or Ab secretion was observed in UV-irradiated mast cell-deficient (Kit^W-sh/W-sh) mice. When mast cell-deficient mice were reconstituted with wild type mast cells, immune suppression was restored. Reconstituting the mast cell-deficient mice with bone marrow-derived mast cells from IL-10–deficient mice failed to restore the ability of UV radiation to suppress GC formation. Our findings demonstrate a function for mast cells, suppression of Tfh cell production, GC formation, and Ab production in vivo.

Background. Up to 60% of the US visitors to Mexico develop travelers' diarrhea (TD). In Mexico, rates of diarrhea have been associated with the rainy

Background: Asthma affects >300 million people globally, including 25 million in the United States. Patients with asthma frequently use the Internet as a source of information. YouTube is one of the three most popular Web sites. Objective: To determine the educational quality of YouTube videos for asthma. Methods: We performed a YouTube search by using the keyword “asthma.” The 200 most frequently viewed relevant videos were included in the study. Asthma videos were analyzed for characteristics, source, and content. Source was further classified as asthma health care provider, other health care provider, patient, pharmaceutical company, and professional society and/or media. A scoring system was created to evaluate quality (−10 to 30 points). Negative points were assigned for misleading information. Results: Two hundred videos were analyzed, with a median of 18,073.5 views, 31.5 likes, and 2 dislikes, which spanned a median of 172 seconds. More video presenters were male (60.5%). The most common type of video source was other health care providers (34.5%). The most common video content was alternative treatments (38.0%), including live-fish ingestion; reflexology; acupressure and/or acupuncture; Ayurveda; yoga; raw food, vegan, gluten-free diets; marijuana; Buteyko breathing; and salt therapy. Scores for videos supplied by asthma health care providers were statistically significantly different from other sources (p < 0.001) and had the highest average score (9.91). Conclusion: YouTube videos of asthma were frequently viewed but were a poor source of accurate health care information. Videos by asthma health care providers were rated highest in quality. The allergy/immunology community has a clear opportunity to enhance the value of educational material on YouTube.

Clinical presentation is key in classifying reactions as either medicated by immunoglobulin E or not.