Alteration of antibody response to pneumococcal polysaccharide type III in rats by neonatal immobilization stress

Our previous studies showed that stressing newborn animals by immobilization during the first 2 weeks of life caused significant changes in the capacity of adult rats to respond to stress as measured by the adrenal and circulating levels of catecholamines. In this report the effect of stress on the antibody response to the capsular polysaccharide of Type III Streptococcus pneumoniae (SSS-III) was investigated in two different strains of rats: Sprague-Dawley (SD) and Fischer (F) 344 rats. Animals were stressed 1 h each day for a total period of 10 days. Following this period of stress, animals were reared together along with littermate controls up to 40 days of age, when they were immunized with an optimally immunogenic dose of SSS-III. The results of experiments done with SD rats showed a substantial suppression of the antibody response when the response of the neonatally stressed animals was compared to the controls. In contrast, stressing adult SD animals for 10 days, followed by a 3-week recovery period prior to immunization with SSS-III, did not result in any significant (p greater than .05) suppression of antibody response. When F rats were used, the antibody response of the neonatally stressed rats was also significantly (p less than .05) lower than that of the controls. Thus, the effects of chronic, immobilization stress on antibody response can be long-lasting when the stressor is applied during the neonatal period.