PREVITE AND BERRY 



Many individuals assume that low environmental temperature 

 plays a role in predisposition to infectious disease. While there 

 is a relative dearth of scientific evidence to support this concept, 

 a few reports have appeared in the literature. Some indicate that 

 cold increases susceptibility to specific infections while others 

 demonstrate an increase in survival following low temperature ex- 

 posure (Girone, 1962), It seemed of import, therefore, to shed 

 further light on this complex problem. The results described below 

 demonstrate the response of cold exposed mice to infection with 

 Salmonella typhimurium, Staphylococcus aureus, and to injection 

 of endotoxins derived from Gram negative bacteria. 



MATERIALS AND METHODS 



During the experimental period, 21 ± 2 gm Garworth farm, CF-1 

 female mice were housed singly and maintained in plexiglass com- 

 partments without bedding. Mice could thus be isolated one from 

 one another so that a group often animals could be housed individu- 

 ally in a total area measuring 8 in, x 10 1/2 in. The importance of 

 single housing (Kulka, 1961) and lack of nesting material (Barnett 

 et al., 19 59) as stress factors in cold studies have been demon- 

 strated. Single housing eliminates the huddling of mice and con- 

 servation of body heat that normally accompanies this activity. Lack 

 of nesting material prevents burrowing and thereby deprives the 

 animal of insulatory material available under usual caging con- 

 ditions, thus accentuating heat loss. The cold exposed animals were 

 maintained in walk-in refrigerators at 5 * 1° C or 15 ± 1° C. Room 

 temperature controls were kept in an air-conditioned laboratory at 

 25 ± 2° C. The animals were given food (Dietrich and Gambrill's 

 pathogen- free mouse biscuits) and water ad libitum. For the single 

 experiment involving high temperature exposure, the mice were 

 placed in compartments held in an incubator with a controlled 

 temperature of 35 ds 2° C, Three liters of air pre- warmed in a 

 water bath were passed through the incubator each minute. The rate 

 of air flow was determined by a flow meter (Fisher), 



216 



