Time relationship between ambient temperature change and antigen stimulation on immune responses of mice

We investigated the time relationship between ambient temperature change and antigen stimulation on immune responses to sheep red blood cells (SRBC) and polyvinylpyrrolidone (PVP) in mice. In the case of a shift from comfortable (25 degrees C) to cold (8 degrees C) temperatures, suppression in the number of splenic plaque-forming cells (PFC) took place mainly when the shift was done between 1 day before and 2 to 4 days after immunization. The suppression of the PVP response lasted for up to a maximum of 6 days when mice were transferred 1 day before immunization. In the case of a temperature shift from 25 degrees to 36.5 degrees C, the suppressive effect was found when the temperature shift was done between 4 days before and 2 days after immunization. The effect lasted longer than that of the temperature shift to cold, i.e., at least 9 days after the temperature shift. Blood corticosterone levels after the temperature shifts corresponded to changes in the immune responses: elevation of the blood corticosterone levels was observed for only the first 3 days after a temperature shift to 8 degrees C but for 10 days after a temperature shift to 36.5 degrees C during the period time of the experiment. These result suggested that blood corticosterone level contributes to the duration of the effects of temperature shifts on immune responses of mice. Furthermore, it appeared that the early stage of the immune response is more susceptible to temperature shifts than the later stage. To explain these results, the terms "effective period" in the course of physiological adaptation to changed ambient temperature and "susceptible period" in the course of the immune response, were proposed.