Geraldine K. Powell

Milk- and soy protein-induced enterocolitis: Evidence for lymphocyte sensitization to specific food proteins

Stimulation ( [3H]thymidine incorporation) of blood lymphocytes cultured with food proteins was evaluated in infants with food protein-induced enterocolitis and correlated with the results of oral diagnostic challenges with the same foods (soy, cows milk, and egg white). The geometric mean stimulation index for lymphocytes from patients with positive oral soy protein challenge that were cultured with soy protein was 8.5, and for patients with positive cows milk challenge the stimulation index was 6.0 when casein was used in the cultures. Both values are significantly different from the values obtained from patients with negative oral challenges (p less than 0.01). The enhanced lymphocyte responses were specific for the food proteins responsible for clinical symptoms. It is not clear whether these lymphocyte responses are due to systemic immunization secondary to macromolecular absorption, or to an abnormality in immune regulation such as a delay in the development of oral tolerance mechanisms. They suggest, however, that circulating lymphocytes sensitive to the food antigens that produce the clinical symptoms are frequent in infants with this discrete form of food protein hypersensitivity.

Enterocolitis in low-birth-weight infants associated with milk and soy protein intolerance.

Two low-birth-weight infants developed a syndrome of vomitting, distension, septic appearance, and bloody diarrhea. Both infants developed symptoms after ingestion of cow milk-based formula initially, and, later, soy-based formulas. These symptoms resolved with intravenous fluids and alimentation. Vomiting, diarrhea, melena, and polymorphonuclear leukocytosis recurred with reintroduction of either milk- or soy-based formulas. This sensitivity persisted throughout the neonatal period and was still present at seven to eight months of age. It appears from these data that intolerance to whole protein formulas can cause a syndrome similar clinically to neonatal necrotizing enterocolitis.

Food Protein-induced Enterocolitis: Altered Antibody Response to Ingested Antigen

Summary: To evaluate the role of immunologic mechanisms in one specific syndrome of food intolerance in infants, food protein-induced enterocolitis, we measured class-specific serum antibodies to three food proteins, ovalbumin, soy, and cow milk, prior to diagnostic food challenges in 18 infants suspected to have this syndrome. Infants with positive challenge reactions to egg, soy, or cow milk had 5–10 times higher levels of IgA antibody directed against that food than did the infants with negative challenges. Levels of IgG antibody to soy and egg were also significantly higher (greater than 10-fold) in infants with positive challenge responses. There was no significant difference in levels of IgM food antibodies between the two groups. IgA anti-soy antibody levels rose in all 12 infants tested 2–10 weeks after a single soy feeding (challenge). However, IgM anti-soy antibody increased in the five infants who had a negative response to the challenge feeding and decreased in those seven with a positive response. The difference between the two groups was statistically significant (P > 0.01). Some correlation existed (r = −0.68) between the increase in IgA anti-soy antibody and the decrease in IgM anti-soy antibody for infants with positive soy challenges. Although a pathogenic role for these antibodies is not proven, the findings suggest an altered immunologic response to ingestion of food antigens in infants with food protein-induced enterocolitis.

Quantitation of fecal carbohydrate excretion in patients with short bowel syndrome

We performed inpatient balance studies in 11 patients to evaluate the role of carbohydrate malabsorption in the pathogenesis of the diarrhea seen in short bowel syndrome. Stool weight, total reducing substance as measured by Clinitest, and total fecal carbohydrate as measured by anthrone were determined. Patients had markedly increased fecal carbohydrate excretion, up to 65% of dietary carbohydrate intake. When the diet contained oligosaccharides, measures of total reducing substance greatly underestimated fecal carbohydrate excretion and were unreliable for quantitation. Stool weight correlated with total fecal carbohydrate excretion and with total reducing substance (r = 0.79, p less than 0.001). Multiple balance studies in 2 patients suggested a relationship between both the amount and type of dietary carbohydrate and fecal carbohydrate excretion. These studies suggest that carbohydrate malabsorption is a major cause of the watery diarrhea and subsequent fluid, electrolyte, and acid-base imbalance seen in patients with short bowel syndrome.

Secretory IgA in the serum of infants with obstructive jaundice

The liver is capable of transporting IgA from the plasma to bile in several experimental animals. After bile duct ligation, SIgA and free secretory component accumulate in the serum of these animals. In the present study, SIgA was found in the serum of all infants with extrahepatic biliary obstruction, and in 75% of those with intrahepatic cholestasis, but in only one of seven age-matched infants without hepatobiliary disease. Infants with EHBO had significantly higher serum levels of secretory IgA and total IgA than in normal infants or patients with IHC. This result suggests that the human liver is involved in SIgA metabolism and that the elevated serum IgA levels in infants with liver disease are caused by bile duct obstruction or proliferation. Quantitation of SIgA in serum may help to differentiate major categories of obstructive jaundice in infancy. The concentration of SIgA in serum was indicative of the site of obstruction in 12 of 19 infants with hepatobiliary disease.

Absorption of food protein antigen in infants with food protein-induced enterocolitis

Increased gastrointestinal absorption of intact antigen with systemic immunization has been considered a major etiologic factor in the development of food sensitivity. We attempted to test this hypothesis in infants with suspected food protein-induced enter colitis by measuring serum ovalbumin (OVA) concentrations after ingestion of egg white (prior to the performance of good challenges to establish this diagnosis). We first noted significant underestimation of serum OVA concentrations in the presence of even low serum anti-OVA antibody concentrations (>1∶12). Next, using selected noninhibitory sera, we found that all infants studied absorbed some OVA, there was no correlation between serum OVA levels and age (3–11 months), and there was no significant difference between serum OVA concentrations in infants who subsequently had positive oral food challenge responses (120 ±67 ng/ml) and a matched group with negative challenges (102 ±80). These data do not support the hypothesis that “intestinal closure” (antigen exclusion) occurs in the neonatal period or the role of antigen absorption as the major etiological factor in the development of food sensitivity. Better methods of quantitating macromolecular absorption must be developed before the role of antigen absorption in food sensitivity can be assessed. Of note, urinary excretion of intact OVA also occurred. This varied greatly from one voiding to the next and continuing for at least 13 hr after ingestion.

A simple spectrophotometric method for quantitative fecal carbohydrate measurement.

A simple quantitative assay was developed for measuring total fecal carbohydrate (CHO) excretion using stools obtained during balance studies performed for fecal fat determination. This spectrophotometric method utilizes Dreywoods anthrone reagent which reacts with equal weights of CHO whether monosaccharide or polysaccharide. Analysis of known dietary CHO solutions yielded greater than 90% of the known theoretical concentration. Recovery of CHO (Polycose) added to fresh stool was greater than 95%, inter-assay coefficient of variation (CV) 6.2%. Stool specimens stored frozen and analyzed over a 21-month period yielded stable results. Fecal CHO excretion/day determined in 32 normal patients, ages 1 month to 13 years, on diets with varying CHO sources, ranged from 0.04 to 0.85 g, average 0.33 g, SD +/- 0.24. Three patients with diseases known to be associated with CHO malabsorption studied showed markedly increased total fecal CHO excretion, up to 53% of their CHO intake. Quantitative fecal CHO excretion in these patients allowed for assessment of the severity of their disease and provided a means for evaluating the use of different dietary CHO sources in their management.

Carbohydrate malabsorption is minimal in school-age cystic fibrosis children

Fifteen school-age cystic fibrosis children, participating in a year-long nutritional management study, were hospitalized at six-month intervals for balance studies during which they continued “free-choice” diets and their usual enzyme supplementation. Stools were analyzed for fat and protein by conventional methods and for carbohydrate using a recently validated anthrone method. Despite persistent fat and protein malabsorption, less than 1% of ingested carbohydrate was lost intact in the stools. Comparison of baseline and placebo balance studies showed fecal excretion of carbohydrate to be independent of intake, in contrast to the fat and protein results. Using a thin-layer chromatography method capable of detecting microgram quantities of urinary organic acids, no short-chain fatty acids were detected in the stool. Further exploration of carbohydrate as a dietary energy source for this patient group with increased energy demands should be pursued.

Effect of prolonged fasting on fatty acid re-esterification in rat intestinal mucosa

Abstract Rats subjected to a three day fast showed marked decreases in total intestinal mucosal protein, mucosal weight, sucrase, maltase and monoacylglycerol acyltransferase activities. Total microsomal protein was decreased to a lesser degree in fasted rats, and total lactase activity remained unchanged. Specific activities of sucrase and maltase were unchanged by fasting; specific activity of lactase increased. Specific activity of monoacylglycerol acyltrans-ferase, expressed per mg microsomal protein decreased. When activity of this pathway was expressed per mg of mucosal protein or mucosal weight it remained unchanged in fasted animals. The results appeared most consistent with the hypothesis of decreased cell proliferation in starvation. A change in the usual proportions of cell types during starvation is also suggested.

Serum D-xylose absorption tests: reproducibility and diagnostic usefulness in food-induced enterocolitis.

We evaluated the use of the D-xylose absorption test as a marker of intestinal mucosal damage following single-dose oral food challenges in infants suspected of food-protein-induced-enterocolitis. The absorption tests were performed before any challenge, and again after each of four separate food challenges. The response to challenge was judged by five objective criteria (diarrhea, polymorphonuclear leukocytosis, fecal blood, leukocytes, and eosinophils). A significant decrease in the group mean for serum xylose was seen following positive challenges. The l-h serum xylose level prior to any challenge was 42 ± 9.5. following negative challenges it was 46 ± 15, and following positive challenges it was 28 ± 4.4, However, there was not a good individual correlation between the challenge response and xylose absorption, so intrasubject variability of the xylose absorption test was examined in six infants who had at least three tests performed before a positive challenge response was encountered. The average standard deviation for these repeated tests was 8.2 mg/dl, and the coefficient of variability was 12.6%. This would suggest that, in utilizing this test to assess mucosal damage following oral food challenges or gluten reintroduction, a decrease of 16 mg/dl from the prechallenge values would have to be seen before the difference would exceed two standard deviations. This degree of change was not seen in any patient following a single oral food challenge.