ABSTRACT
Two groups of albino rats were included. The control group is formed of nine albino rats, divided into three subgroups: 1] Primed [sensitized] only by intraperitoneal injection of soybean protein emulsion, 2] duodenal tube feeding for 14 days by soybean protein hydrolysate only, and 3] oral feeding by soybean protein-free milk formula. The test group formed of nine albino rats were primed by intraperitoneal injection of soybean protein emulsion and challenged after one week by duodenal tube feeding of soybean protein hydrolysate for 14 days or till diarrhea developed. Results showed that all control groups showed no pathological abnormalities in their duodenum and did not develop diarrhea. The test group showed basically similar changes that varied in severity from mild, moderate to marked. The immunological findings were humoral and cellular immume reaction. Edema of the duodenum erythema and reduction in the size of the villi were seen morphologically. Ultrastructurally, deposition of immune complexes in the basement membrane leading to its thickening and irregularity, adhesion of leukocytes [PNLs, monocytes and lymphocytes] to the injured endothelium, edematous corium and inflammatory cellular infiltrate, increase in the number of lymphocytes going to the surface and congested plugged blood vessels were seen