Edible legumes contain several growth inhibitory factors which cause intestinal malabsorption and weight loss in animals: adverse effects which are ameliorated in the germ free state. Purified phytohemagglutinin of red kidney bean isolated by sequential sepharose thyroglobulin affinity and ion exchange chromatography will be used to define whether antinutritional effects depend on (a) binding of the glycoprotein PHA lectin to the microvillus membrane of the small intestine and (b) subsequent adhesive interaction with enteric bacteria. Growth failure and malabsorption will be studied by feeding highly purified PHA or the specific isolectins, mitogenic (L4) and erythroagglutinating (E4) to conventional and germ free weanling rats and will be validated by studies of lipid and protein absorption utilizing balance experiments and 14C-triolein and 3H-oleic acid, 57Co-VitaminB12, 14-C-L-leucine and 14C-L-alanine. Quantitative and qualitative changes in aerobic and anaerobic small intestinal bacterial flora and the population density of blood group degrading bacterial will be measured. Bacterial adherence to mucosal slices and brush border membranes will be measured in vitro employing specific carbohydrate inhibition. Bound E-PHA will be identified in mucosal tissue using specific immunofluorescent staining. 125-I-E-PHA binding to microvillus membranes will be measured. Inhibition of specific saccharides will employ the monosaccharide N-acteyl-galactosamine as well as fetuin, human transferrin glycopeptide and human erythrocyte glocopeptide I. In addition, binding will be measured in animals with protein malnutrition and acute experimental diarrheal states. Identification of the E-PHA microvillus membrane receptor will use solubilization of membrane proteins by sodium dodecyl sulfate (SDS) and separation of polyacrylamide gels (PAGE). Identification of glycoproteins on SDS-PAGE will utilize a technique of overlaying with 125-I-E-PHA or fluoroscein conjugated E-PHA. These processes may be comparable to the dietary effects of other proteins in certain human intestinal disorders.