Quantifying Intraepithelial Lymphocytes with CD3 Marker: Insights into Marsh Classification in Celiac Patient

Early celiac alterations may be difficult to diagnose via mucosal biopsy due to the overlapping nuclei of enterocytes and intraepithelial lymphocytes (IELs). CD3 was suggested as an intraepithelial lymphocytosis marker. Aim: To evaluate CD3 immunohistochemical marker for IELs to confirm Marsh categorization of celiac disease. Methods: A cross-sectional observational comprised 52 routine diagnostic duodenal biopsies from Al-Hilla Teaching Hospital, Al-Imam Al Sadiq Hospital, and private laboratories that were “consistent with” or “suggestive of” celiac disease. Clinical and demographic data from patient records were obtained for all instances. All sections were CD3-stained immunohistochemically. IELs were examined for 100 enterocytes in hematoxylin and eosin (H&E) slides and CD3. Results: Patients aged 18-48 years, with a mean of 25.2 (±12.53) years, and a male-to-female ratio of 1:1.6. Marsh I was 17 (32.7%), Marsh II and IIIc were 10 (19.2%), and Marsh IIIa and b were 15.4% and 13.5%. In H&E sections, the IELs count was 38.8 (± 7.4) cells, whereas CD 3 immunostaining showed 47.10 (±7.0) cells (P<0.001). CD3 IELs counts correlated well with H&E (r=0.842). However, CD3 counts were consistently higher, with a mean difference of -8.29 cells and significant dispersion (P<0.001). CD3 detected more lymphocytes than H&E regardless of age, sex, or Marsh group. Higher significance was seen in Marsh I (P<0.001) and II (P=0.005). Conclusions: CD3 immunostaining improved IELs counting. Marsh I shows a greater CD3 IELs count than H&E. Thus, CD3 immunostaining may diagnose early celiac disease in individuals with positive serology and Marsh 0 or borderline lymphocytosis.