A high fat diet exacerbates stress-induced changes in immune function

Stress has been shown to alter a variety of immunological responses. While a number of stressors and immune responses have been investigated, the possible contribution of nutrient effects on stress-induced immune modulation has not been explored. Here we describe two model systems for investigating these interactions. Splenocytes collected from rats subjected to REM-sleep deprivation exhibited significant suppression of their blastogenic response to the mitogens concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM). Maximal suppression of splenocyte proliferation occurred after 72 hours sleep deprivation. Addition of recombinant interleukin 2 (IL-2) to the cultures failed to restore the proliferative response. Rats vaccinated with maltose binding protein immediately prior to sleep deprivation also exhibited significant depression of their humoral and cell-mediated immune response to vaccination. As little as 24 hours of sleep deprivation caused reduced responsiveness to the vaccine. Rats restrained in plastic tubes also exhibited decreased blastogenic responses to mitogens. While cell surface expression of the IL-2 receptor was elevated in the splenocyte cultures from stressed rats, supplementation of the cultures with IL-2 likewise failed to restore the proliferative response to the mitogens. Rats fed a high fat diet exhibited exacerbated stress-induced immune modulation when compared to rats fed a low fat diet.