Counting Intraepithelial Lymphocytes: A Comparison Between Routine Staining and CD3 Immunohistochemistry

Abstract

Counting intraepithelial lymphocytes (IELs) is a key part of the assessment of duodenal biopsies. Immunohistochemistry (IHC) for CD3 can aid identification of lymphocytes in this context, but it is not evident that counts on hematoxylin and eosin (H&E) and CD3 are comparable. This study aimed to compare the IEL counts in duodenal biopsies using H&E stains and CD3 IHC, and to examine the interobserver variability. Thirty-five paired H&E and CD3 sections were reviewed by 6 pathologists who counted the number of IELs per 100 enterocytes. The counts were categorized into groups: normal (<25 lymphocytes), mildly raised (25-40 lymphocytes), and markedly raised (>40 lymphocytes). CD3 IHC was associated with significantly higher IEL counts than H&E. Four cases with normal H&E counts had raised counts with CD3. There was moderate agreement between observers for both H&E and CD3. Lack of concordance between CD3 and H&E IEL counts suggests that counts derived from the 2 methods may not be comparable to each other and should not be considered equivalent. There was no significant improvement in interobserver variability with CD3 IHC.

Immunohistochemical analysis of intestinal biopsies in individuals with celiac disease

“…The difference was highly significant ( P = 0.001) and the counts were lower than the counts in the study conducted by Cooper et al . in the United Kingdom, 16 which were 35.2 (95% CI = 30.0–40.8) by H&E and 49.7 (95% CI = 44.1–55.3) by CD3 IHC.…”

Aktualisierte S2k-Leitlinie Zöliakie der Deutschen Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS)

“…Es sei jedoch darauf hingewiesen, dass sich der Grenzwert von 25 IEL/100 Epithelien auf die Quantifizierung der IEL im HE-Schnitt bezieht. Studien zur Frage der Vergleichbarkeit der Lymphozytenzahl in der konventionellen und immunhistologischen Färbung mit CD3 weisen auf eine um den Faktor 1,5 höhere IEL-Zahl hin, wenn anhand der Immunhistologie ausgewertet wird 210 211 .…”

“…3.2 Modifizierte Marsh-Oberhuber-Klassifikation mit modifiziertem Grenzwert für die Anzahl intraepithelialer Lymphozyten (IEL). Frage der Vergleichbarkeit der Lymphozytenzahl in der konventionellen und immunhistologischen Färbung mit CD3 weisen auf eine um den Faktor 1,5 höhere IEL-Zahl hin, wenn anhand der Immunhistologie ausgewertet wird[210,211].…”

Microscopic colitis in older adults: impact, diagnosis, and management

“…We would also like to point out that using different staining methods – other than classic HE – can increase the diagnostic sensitivity (in particular, CD3 staining) as they allow the identification of more intraepithelial lymphocytes. 35 , 36 Furthermore, as demographic trends in Western societies have shown an increase in the proportion of the elderly, this phenomenon might also contribute to the increased incidence of MC (as the disease typically affects people past the age of sixty).…”