Effects of chromium and copper depletion on lymphocyte reactivity to mitogens in diabetes-prone BHE/cdb rats.

OBJECTIVE: The purpose of this study was to measure effects of chromium (Cr) and copper (Cu) depletion on lymphocyte reactivity to mitogens in diabetes-prone BHE/cdb rats. METHODS: A 2 x 2 factorial research design was used, and 40 BHE/cdb rats were fed with Cr- and/or Cu-depleted diets or adequate Cr and/or Cu diets for 21 wk. Cr and Cu concentrations in diets and mineral concentrations of tissues of BHE/cdb rats were measured by using flame and graphite furnace atomic absorption spectrometry. Three glucose tolerance tests were performed to monitor the development of diabetes or glucose intolerance at weeks 12, 18, and 21. Splenocytes (2 x 10(6)) were incubated with phytohemagglutinin-l (PHA-L), concanavalin A (ConA), and lipopolysaccharides (LPSs), respectively, for 72 h. Four hours before the end of the incubation, splenocytes were pulsed with 3H-thymidine. The 3H-thymidine uptake by lymphocytes was used to calculate a stimulation index. RESULTS: According to glucose tolerance tests, these rats did not develop diabetes or impaired glucose tolerance throughout the study. Average Cr concentrations were 0.98 to 1.03 mg Cr/kg of diet in adequate Cr diets and 8.2 to 14 micrograms Cr/kg of diet in Cr-depletion diets. Average Cu concentrations were 3.6 to 6.4 mg Cu/kg of diet in adequate Cu diets and 1.1 to 1.3 mg Cu/kg of diet in Cu-depletion diets. Organ weights did not differ significantly among treatment groups at the end of the study. Cr or Cu depletion significantly affected iron, zinc, and magnesium concentrations in the liver. A significant interactive effect of Cr and Cu was observed on lymphocyte proliferation with PHA-L stimulation at 25 micrograms/mL (P < 0.006). However, there were no significant effects of dietary treatment on lymphocyte proliferation with 10 micrograms/mL of PHA-L, ConA, or LPS stimulations. CONCLUSIONS: When Cr and Cu were adequate in the diets, there was an enhanced effect of Cu or Cr on lymphocyte proliferation. However, when Cr was depleted in the diet, there was a suppressive effect of Cu on lymphocyte proliferation. This result indicates that adequate amounts of Cr and Cu in the diet support the immune system.

Effect of laser thermal injury on Langerhans cells in mouse and hairless guinea pig epidermis.

To examine the effect of laser thermal injury on Langerhans cells (LC) within the epidermis, the dorsal skin of mice and hairless guinea pigs was exposed to varying levels of laser irradiation using a thulium laser at a wavelength of 2.0 µm. At 6, 24 and 48 h post irradiation, animals were euthanized, skin samples prepared for histology and the epidermis obtained and stained by major histocompatibility complex-II staining (mice) or ATPase assay (hairless guinea pigs) for the enumeration of LC. Mouse skin exhibited histological evidence of thermal damage at 24 h post irradiation at even the lowest dose (0.14 W) and decreases in the numbers of epidermal LC were observed at all doses and decreases were proportional to dose. In contrast, hairless guinea pig skin only showed consistent histological evidence of thermal damage at the highest dose of irradiation (0.70 W) at 24 and 48 h post irradiation and exhibited a statistically significant decrease in numbers of epidermal LC only at this dose. Thus, epidermal LC depletion occurred in the skin of both mice and hairless guinea pigs in response to laser treatment and the magnitude of depletion directly correlated with the extent of thermal damage both within and between species.