Immunological responses to fed protein antigens in mice. IV. Effects of stimulating the reticuloendothelial system on oral tolerance and intestinal immunity to ovalbumin.

We have studied the role of the reticuloendothelial system (RES) in intestinal and systemic immunity in mice immunized orally with ovalbumin (OVA). Stimulation of the RES by oestradiol completely prevented the induction of systemic tolerance normally found in mice fed 25 mg OVA and this applied both to humoral immunity and delayed-type hypersensitivity (DTH). In addition, an active DTH response could be detected in the mucosa and mesenteric lymph nodes (MLN) of oestradiol-treated, OVA-fed mice on oral challenge with OVA. Oestradiol had no direct effect on lymphocyte function and we propose that RES activation may be one mechanism which predisposes to small intestinal disease associated with food hypersensitivity.