Autoimmunity with immunodeficiency: a logical paradox

Diarrheal Illness in the Pediatric Population: A Review of Neonatal Enteropathies and Childhood Idiopathic Inflammatory Bowel Disease

In the clinical context of pediatric diarrheal illness, the interpretation of endoscopic mucosal biopsies varies significantly from that in adults. This review outlines these differences by first describing a host of diarrheal illnesses that are nearly exclusive to the pediatric age group. The final portion of this article describes salient pathologic differences between adult and pediatric idiopathic inflammatory bowel disease. The goal of this review is to provide a brief description of each disease process and focus on practical aspects of diagnosis that are applicable for pathologists working in general practice settings.

The role of histopathology in diagnosing protracted diarrhea of infancy

Protracted diarrhea is used to describe infants with loose and frequent stools of sufficient severity to require nutritional support, most commonly parenteral nutrition. Despite similar clinical presentations, the causes of protracted diarrhea in infants are varied and diverse in management and prognosis. The following cases represent the two more common causes of protracted diarrhea in young infants in the developed world - allergic and autoimmune enteropathy. Both patients demonstrate diagnostic challenges related to clinical and/or laboratory features. These cases illustrate the important role histological assessment plays in determining the correct diagnosis, treatment course and prognosis in infants with protracted diarrhea.

The nature of colitis in chronic granulomatous disease

BACKGROUND

Patients with chronic granulomatous disease (CGD) may have gastrointestinal manifestations, commonly colitis. The etiology, prevalence, and inflammatory process of CGD colitis are unclear.

OBJECTIVES

To characterize the inflammatory process of CGD colitis and to compare it with other inflammatory bowel disorders.

METHODS

Colonic mucosal biopsies from 8 CGD patients were immunostained for eosinophils, neutrophils, macrophages, and adhesion molecules (ICAM; VCAM, E-selectin) and compared with normal and diseased controls (allergic colitis, ulcerative colitis, and melanosis coli). Cell types were counted and expressed as cell/mm2.

RESULTS

The inflammatory infiltrate in CGD colitis differed from the normal controls by an increase in eosinophils (110; 48-176 [median and range] versus 14.5; 3-30; P < 0.005) and macrophages (291.5; 203-480 versus 38.5; 27-64; P < 0.005). There was a paucity of neutrophils compared to ulcerative colitis (10; 0-101 versus 315.5; 78-688; P < 0.005). Expression of HLA-DR was increased in the epithelium and vascular endothelium in CGD compared with normal controls. Patterns of expression of the adhesion molecules differed significantly in CGD from those in other inflammatory bowel diseases: intracellular adhesion molecule-1 was more strongly expressed in the lamina propria, vascular adhesion molecule-1 was more patchily expressed, and E-selectin was present only in the small vessels.

CONCLUSIONS

The mechanism of inflammation and profile of inflammatory mediators in CGD colitis differs from that in other inflammatory bowel diseases.

Celiac disease and immunoglobulin a deficiency: how effective are the serological methods of diagnosis?

Immunoglobulin A (IgA) deficiency is 10 to 15 times more common in patients with celiac disease (CD) than in healthy subjects. Serological tests have become the preferred methods of diagnosing CD in both symptomatic and asymptomatic patients. However, commercially available serological methods are limited in that they detect only the IgA isotype of antibodies (with the exception of IgG gliadin assays); hence, IgA-deficient patients with CD may yield false-negative serology. Fifteen pediatric patients with CD and 10 IgA-deficient pediatric patients without CD were examined for IgA and IgG antibodies to endomysium, gliadin, and tissue transglutaminase. Twenty-five specimens from patients with IgA deficiency were examined. Fifteen were from patients with CD, and 10 were patients without CD. All 15 IgA-deficient patients with CD were positive for endomysium antibodies of the IgG isotype and for IgG gliadin antibodies. All but one of the IgA-deficient patients with CD were also positive for IgG tissue transglutaminase antibodies. None of the IgA-deficient patients without CD were positive for any of the antibody markers. All the specimens examined were also negative for IgA-specific antibodies to endomysium, gliadin, and tissue transglutaminase. IgG-specific antibody tests for endomysium, gliadin, and tissue transglutaminase are useful for the identification of IgA-deficient patients with CD. IgG antibody tests along with tests routinely being used in clinical laboratories can reliably detect all active patients with CD. In addition, the levels of these CD-specific IgG antibodies could be used to monitor patient dietary compliance.