Whole-body exposure of normal subjects to erythemogenic doses of UV-B radiation results in a decrease in the proportion of circulating E-rosette-forming lymphocytes, an increase in the proportion of null cells and a decreased incorporation of tritiated thymidine into DNA of lymphocytes following stimulation by phytohaemagglutinin (PHA). These alterations are dose-dependent, appear soon after exposure, reach a maximum after 8-12 h, and are reversed by 48-72 h post exposure.

Exposure of guinea pigs to UVA (320--400 nm) radiation following administration of 8-methoxypsoralen by gavage (referred to by the acronym, PUVA) or exposure to UVB (290--320 nm) radiation, produced suppression of the cutaneous delayed hypersensitivity reaction at the site of exposure to radiation and at distant nonexposed sites. In these experiments, the animals were immunized by injection of dinitrophenyl-bovine gamma-globulin (DNP-BGG) in complete Freund's adjuvant and delayed hypersensitivity responses were provoked by intradermal injections of DNP-BGG, DNP and BGG on the flanks. Exposure to erythemogenic doses of either PUVA or UVB radiation for 7 days prior to immunization and for the 7 days between immunization and challenge (total period of radiation: 14 days) produced inhibiton of responses to each of the test substances. In addition, treatment with erythemogenic doses of PUVA either for 7 days prior to immunization or during the interval between immunization and challenge with DNP-BGG, inhibited the delayed hypersensitivity responses at the site of irradiation and at a nonexposed site. These findings suggest that in vivo exposure to nonionizing radiation leads to both local and systemic alteration of certain immune responses.

The electrical conductivity of the charge transfer complex between iodine and polyphenylacetylene (PPA) has been studied. The room temperature d-c conductivity (0) increased by seven orders of magnitude with iodine addition, reaching a maximum of 10-R -I . cm-I for a 1 : 1 ratio of iodine to repeating unit, and its concentration dependence could be described by:where c is the mole fraction of iodine. Both crystalline and amorphous cis-PPA followed this form, the crystalline polymer having a lower conductivity at low iodine levels, but attaining the same maximum value. The trans-polymer iodinated much less readily than cis-PPA. Molecular weight variations did not influence iodine uptake or conductivity in the range studied. It was possible to remove virtually all iodine from the chargetransfer complex in dynamic vacuum, and an iodine diffusion coefficient of D = 10-' ' cm2. s ~ ' was determined from the rate of weight loss. Passage of current resulted in the evolution of iodine and iodine compounds at the anode. The experiment is consistent with a predominantly ionic conduction mechanism, in which the strong concentration dependence of u is associated with a concentration-dependent activation energy for ionic charge-carrier formation.

Three parameters of immune function--enumeration of circulating T and B lymphocytes and response of lymphocytes to graduated doses of phytohaemagglutinin (PHA)--were examined serially in eleven patients with psoriasis before, during, and after an intensive course of PUVA therapy. A trend was detected for the lymphocyte response to PHA to fall during the first week of treatment and then rise back towards the pre-treatment level. No alteration was found in the percentage or absolute numbers of circulating T and B lymphocytes. This study shows that routine PUVA therapy can induce an alteration in immune function but that this alteration is slight and short-lived.

Four groups of female Dutch-belted rabbits (Oryctulagus cuniculus) were given methoxsalen (12 mg/kg) or placebo by oral intubation and 1 hr later were exposed to UVA for either 2 or 8 hr. This procedure was repeated 5 days each week for 18 mo. A fifth group received no drug and no UVA exposure. The skin of the animals given methoxsalen and UVA showed signs of acute and chronic phototoxicity. Multiple peripheral blood parameters of hepatic, renal and hematologic function were normal and were not different between groups. Complete ophthalmoscopic examinations were performed periodically. No cataracts were seen in any of the animals. This data provides the perspective that in one species the daily dose of methoxsalen and UVA required to induce chronic cutaneous photosensitization is lower than the daily dose required to induce cataracts. It is inadvisable to interpret this data as suggesting that no risk exists for patients being treated with oral methoxsalen photochemotherapy. The experimental evidence supporting photosensitization as a cause of cataracts and implicating a role of lens DNA in this cataractogenesis is reviewed. Because methoxsalen-UVA alterations of lens DNA or protein could lead to delayed onset of cataracts, and because of the serious nature and potential preventability of phototoxic lens opacification, appropriate protective eye wear is recommended for all patients receiving oral psoralen photochemotherapy.