[651] Role of Antigen Presenting Cells in the Pathogenesis of Adult Eosinophilic Esophagitis A Single Institutional Study of 285 Patients

DT Patil, J Liao, N Gonsalves, I Hirano, MS Rao, GY Yang. Northwestern University, Chicago, IL

Background: Although primarily idiopathic in nature, adult eosinophilic esophagitis (EE) is a distinct clinicopathologic entity known to be associated with ingested allergens, reflux, drugs, or infectious agents. Evidence indicates that immune dysregulation is the main pathogenetic mechanism and mucosal CD1a antigen presenting cells (APC) are part of this pathway. In this study, we analyzed the role of APC in pathogenesis of adult EE and correlated the findings with histological classification and diet elimination trial data.
Design: Our aim was to a) evaluate density of CD1a cells in EE, b) compare the density between distal-predominant EE and reflux esophagitis (RE), & c) measure APC response to diet elimination therapy in a 10 patient cohort non-responsive to PPI Rx (ongoing trial). The diagnostic criteria for EE were: at least 1 biopsy fragment with >25 eos/hpf or 15 eos/hpf in 3 consecutive fields. Age, biopsy location, basal cell hyperplasia (BCH), spongiosis and max.no.of eos./hpf were noted. CD1a+APC were determined using avidin-biotin-peroxidase immunohistochemistry with appropriate controls and expressed as max. no. of CD1a+ cells/hpf.
Results: We reviewed 424 biopsies from 285 patients (193 males, 92 females) over a 5-yr period. There were 97 cases of distal-predominant EE while 188 patients showed both proximal and distal esophageal involvement (diffuse pattern EE). CD1a cells were mainly located in the peri-papillary area. There was a significant difference between max. no.of CD1a +cells/hpf in normal mucosa (7.253.1) and RE (16.24.6, p=0.01) and EE (34.417.8, p=0.003). There was no association between density of APC and eosinophilic infiltrate, BCH or spongiosis. When compared to diffuse pattern EE (3017), a significantly more CD1a+ cells were seen in distal-predominant EE (4017.5, p=0.03). Similarly, higher number of CD1a+ cells were noted in distal-predominant EE compared to RE (p=0.006). Although the max. no.of eos./hpf significantly improved post diet elimination (p=0.03), no such difference was found with density of APC.
Conclusions: Our results indicate that APC play a key role in pathogenesis of EE. The CD1a cell distribution pattern suggests that process of antigen presentation is distal predominant and CD1a may serve as a useful marker to distinguish EE and RE. Although diet elimination trial does not alter the number of CD1a cells, further study of functional APC distribution is warranted.
Category: Gastrointestinal

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 103, Monday Morning