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PubMedDate not supplied

Sunlight, immunosuppression and skin cancer: role of histamine and mast cells.

1. The development into tumours of skin cells transformed by ultraviolet (UV) B radiation of wavelengths 290-320 nm is enhanced by the ability of UVB to suppress an immune response that would otherwise destroy them. Ultraviolet B-induced immunomodulation may be by multiple mechanisms, but generally manifests in an antigen-presenting cell defect and an altered cytokine environment in the draining lymph nodes. 2. Immune responses to microbial or self-antigens may be dysfunctional by similar mechanisms following UVB exposure. 3. Earliest-acting intermediates in the initiation of UVB-induced immunosuppression are the UVB absorbers (photoreceptors) of the skin, notably DNA resulting in immunoregulatory cytokine production, and trans-urocanic acid (UCA), which, upon isomerization to its cis isomer, signals downstream immunosuppressive events. 4. In mice, dermal mast cells are critical to UVB-induced systemic immunomodulation. In mice, there is a functional link as well as a linear relationship between the prevalence of histamine-staining dermal mast cells and the log of the dose of UVB required for 50% immunosuppression. Studies with histamine receptor antagonists support histamine as the main' product of mast cells involved. Histamine acts in large part via a prostanoid-dependent pathway. 5. Approximately 50% of humans and greater than 90% of patients with non-melanoma skin cancer are UVB susceptible for suppression of a contact hypersensitivity response. Neither cytokine polymorphisms nor UVB-induced levels of cis-UCA in irradiated skin have been linked to UVB susceptibility. Patients with basal cell carcinomas (BCC) have an increased dermal mast cell prevalence in non-sun-exposed buttock skin. We propose that mast cells function in humans, as in mice, by initiating immunosuppression and, thereby, allowing a permissive environment for BCC development.

Animals↗
PubMed2000

Retinoblastoma incidence and sunlight exposure.

To evaluate positive findings from an earlier report, we studied the relation between retinoblastoma incidence and ultraviolet (UV-B) radiation levels in the Surveillance, Epidemiology, and End Results (SEER) programme areas of the USA using weighted regression, as well as in international data after adjusting for race, economic development, and climate. The association was not statistically significant within the USA (P > 0.20). At an international level, the relation was significant overall and after adjusting for economic development, but it was not significant after adjusting for race and tropical climate, suggesting that environmental factors other than UV-B may be responsible for the geographic patterns of retinoblastoma.

Adolescent↗
PubMed1988

[Modification of the course of chronic intraocular inflammations by sunlight (Israel study)].

Natural treatment methods are currently becoming more and more interesting, in part due to recent results of experimental and clinical research. It has been shown that light of certain wavelengths has a systemic immunosuppressive effect. It therefore seemed logical to expose patients suffering from chronic iridocyclitis or intermediate (peripheral) uveitis to high doses of solar radiation. Following a stay in Israel (Dead Sea), a transient increase in visual acuity was observed. Inflammatory activity and the number of inflammatory attacks decreased. This could be the first step toward a more "physiological" method of immunosuppression in the treatment of chronic uveitis.

Adolescent↗
PubMed1990

Sunlight, sunburn, and sunscreens. Preventing and remedying problems from 'too much fun in the sun'.

Exposure to ultraviolet (UV) radiation is a dose-related risk factor for the development of several cutaneous cancers. This risk is reduced by avoiding exposure to the sun and by the use of sunscreens. The latter products are rated according to their ability to protect skin from developing erythema. Treatment of overexposure is geared to relief of symptoms. Preventive measures, however, should always be encouraged.

Humans↗
PubMedDate not supplied

Bobber: a cervical ataxic mutant in the domestic turkey responsive to sunlight.

Bobber is a genetic disorder in the domestic turkey that is usually expressed between two and four weeks of age. The condition is permanent and is characterized by ventrocaudad bending of the neck accompanied by a lateral pendulumlike motion of the head between the legs. Expressivity of the defect is variable and may be exhibited in some turkeys as a stargazing posture or a rapid clockwise twirling motion. When suspended by the legs in a head-down orientation, afflicted turkeys exhibit an inward turning of the neck and head toward the breast as opposed to an outward turning in normal turkeys. The disorder is inherited as a sex-linked recessive trait. The symbol bo is used for the gene. The defect can be corrected by exposure to intense light in the visible spectrum.

Animals↗
PubMed1997

Heavenly sunlight.

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Christianity↗