Comfortable and Partial Warm Environment Increases Salivary S-IgE Concentration in Healthy Adults

Abstract An indoor thermal environment stimulates the human endocrine system, thermoregulation system, and nervous system, which significantly affects immunity. However, the effect of environmental temperature on immunity was not included in the field study of thermal comfort. To achieve this, we considered three different temperatures (18, 24, and 30 °C). Skin surface temperature, unstimulated whole saliva, thermal sensation vote, and thermal comfort vote from ten subjects under each condition were acquired simultaneously. The same subjects and experiment were repeated once in different years. Salivary secretory immunoglobulin E (S-IgE) concentration was measured using an enzyme-linked immunosorbent assay. Our results indicate that environmental temperature significantly affected salivary S-IgE concentration (P = 0.015), When the environmental temperature increased from 18 to 24 to 30 ℃, the IgE concentration in saliva gradually increased. The S-IgE concentration was the highest when the thermal sensation and thermal comfort were close to neutral and comfortable, which was 143.7% higher than the very uncomfortable. The S-IgE concentration was significantly positively correlated for thigh, back, forehead temperature, and average skin temperature (P = 0.023, P = 0.045, P = 0.021, P = 0.018, respectively). A comfortable and warm environment may enhance oral mucosal immunity by increasing the concentration of S-IgE in the saliva.