Background：Climate affects cell-mediated cellular immunity and antibody-mediated humoral immunity. As basic units of humoral immunity, antibodies regulate pathogens and prevent infection, which affect human health. However, the influence of atmospheric temperature and temperature differences on antibodies is still unclear. We provide basic evidence on this topic by analyzing the effects of ambient temperature on immune indexes and mortality.
Method：Based on the physical examination data of a general hospital in a large city in China from January 1, 2018 to December 31, 2019, we analyzed the influence of atmospheric temperature and temperature differences from climatic factors on the concentrations of four kinds of antibodies (IgA, IgM, IgG and IgE) through an epidemiological survey. Relationships between the atmospheric temperature and mortality in the hospital and city were also discussed. On this basis, we explored the relationship between each immunoglobulin and the mortality rate in the hospital and city. To further verify the effects of ambient temperature on IgE related to respiratory system immunity, we designed a field experiment with an artificial environment near the human thermal comfort zone.
Results: The changes of IgM and IgE have seasonal characteristics. There was a significantly positive correlation between ambient temperature and IgE concentration related to respiratory immunity in natural and artificial environments (natural environment: P=0.021, R²=0.428 in; artificial environment: P=0.009, Spearman=−0.495). The IgM and IgE levels were the inverted "U" type with the temperature difference, while the IgA and IgG levels were the "fishbone" type. The IgM and IgE concentrations were the highest when the temperature difference was equal to zero. The mortality rate of the hospital and city was U-shaped with the season, and the mortalities were strongly negatively correlated with local atmospheric temperature (hospital: P=0.006, Spearman=-0.544**; city P = 0.000, Spearman = 0.743 **). The concentration of IgE related to respiratory system immunity was significantly negatively correlated with the hospital and city mortalities (hospital: P=0.014; city: P=0.048). IgE levels can be used as a biological parameter to predict death.
Conclusions: Low temperature and large increases or decreases in temperature are not conducive to the secretion of antibodies, especially IgE related to respiratory immunity, which can increase the mortality rate to some extent. In the future, based on the findings of our artificial environment study, the span between stressors can be narrowed to determine the temperature range that can cause changes in antibody concentrations. Thus, the duration and lag time of the influence of each temperature on human immune indexes were studied, as well as how the immune indexes changed.

Environment temperature; Temperature difference; Antibody; Mortality; Respiratory system; Immunity