Here we present a new method to accurately measure body temperature differences in passive systemic anaphylaxis (PSA) and food allergy mouse models using an infrared thermometer. This procedure has been accurately duplicated in previous PSA results.
This methodology helps address key questions in the field of allergy and immunology, specifically those that are regarding phenotypes that may be associated with body temperature changes. The main advantages of this technique are that it is inexpensive, non-invasive, and does not require anesthesia. The implications of this technique allow researchers to reduce the stress and pain of mice during temperature measurement while eliminating the effects of anesthesia, and/or to visualize behavioral phenotypes.
To measure the mouse body temperature after anesthesia, confirm sedation by respiratory rate or immobility and grasp the mouse by the nape of the neck with an index finger and thumb and the tail with a pinky finger. While holding the mouse parallel to the lab bench surface, place an infrared thermometer sensor below the lower abdomen with the outer flat surface of the thermometer two to five millimeters away from the surface of the abdomen between the two upper nipples. Then depress the trigger of the thermometer to measure the temperature of the animal, taking care to keep the mouse and the thermometer steady.
To measure the mouse body temperature without anesthetic, pick the mouse up by the middle of the tail and expose the abdomen. Allow the mouse to hold on to a straight edge surface with its forepaws and hold the trigger to measure the temperature. Alternatively, allow the mouse to hold on to the upper straight edge of the thermometer and make the mouse sit on the outer flat surface of the thermometer with it's abdomen just over the infrared sensor during the temperature measurement.
For a passive systemic anaphylaxis sensitization use a one milliliter syringe equipped with a 26 gauge needle to inject 200 microliters of freshly prepared Anti-Dinitrophenol, or DNP, IgE in PBS, into the peritoneum of each recipient animal just lateral to the midline between the most inferior and second most inferior nipples. 24 hours after injection, measure the body temperature of each recipient animal as demonstrated, and load a one milliliter syringe equipped with a 30 gauge needle with 100 microliters of freshly prepared DNP human serum albumin. To induce passive systemic anaphylaxis, insert the needle on the medial side of the eye at a shallow angle aiming behind the eye, and inject the entire volume of solution intravenously into the retro-orbital venous sinus.
Then place the mouse alone in a recovery cage with monitoring until full recumbency, and measure the body temperature and activity every 10 minutes for 70 minutes. IgE sensitized mice demonstrate a maximum temperature drop of three degrees Celsius at 20 minutes while PBS control mice exhibit a maximum drop of 1.1 degrees Celsius within the same time period after challenge. Behavioral observations can also be performed in non-anesthetized animals to assess the relationship between the observed temperature drops and the mouse activity.
In this representative mouse food-allergy challenge, the PBS control group demonstrated a significant temperature drop 10 minutes after challenge compared to the 2CA inhibitor treated group. Evaluation of the activity scores and temperature drops from this food allergy challenge revealed a statistically significant correlation between the two sets of data. Following this procedure, other experiments involving mouse body temperature measurements can be performed to answer additional questions regarding behavioral phenotypes that are associated with body temperature change.
