AIM:To investigate colonic endocrine cells in lymphocytic colitis(LC) patients.METHODS:Fifty-seven patients with LC were included.These patients were 41 females and 16 males,with an average age of 49 years(range 19-84 years).Twenty-seven subjects that underwent colonoscopy with biopsies were used as controls.These subjects underwent colonoscopy because of gastrointestinal bleeding or health worries,where the source of bleeding was identified as haemorrhoids or angiodysplasia.They were 19 females and 8 males with an average age of 49 years(range 18-67 years).Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy.Biopsies were fixed in 4% buffered paraformaldehyde,embedded in paraffin and cut into 5 m-thick sections.The sections immunostained by the avidin-biotin-complex method for serotonin,peptide YY(PYY),pancreatic polypeptide(PP) enteroglucagon and somatostatin cells.The cell densities were quantified by computerised image analysis using Olympus software.RESULTS:The colon of both the patient and the control subjects were macroscopically normal.Histopathological examination of colon biopsies from controls revealed normal histology.All patients fulfilled the diagnosis criteria required for of LC:an increase in intraepithelial lymphocytes(> 20 lymphocytes/100 epithelial cells) and surface epithelial damage with increased lamina propria plasma cells and absent or minimal crypt architectural distribution.In the colon of both patients and control subjects,serotonin-,PYY-,PP-,enteroglucagon-and somatostatin-immunoreactive cells were primarily located in the upper part of the crypts of Lieberkühn.These cells were basket-or flask-shaped.There was no statistically significant difference between the right and left colon in controls with regards to the densities of serotonin-and PYYimmunoreactive cells(P = 0.9 and 0.1,respectively).Serotonin cell density in the right colon in controls was 28.9 ± 1.8 and in LC patients 41.6 ± 2.6(P = 0.008).In the left colon,the corresponding figures were 28.5 ± 1.9 and 42.4 ± 2.9,respectively(P = 0.009).PYY cell density in the right colon of the controls was 10.1 ± 1 and of LC patients 41 ± 4(P = 0.00006).In the left colon,PYY cell density in controls was 6.6 ± 1.2 and in LC patients 53.3 ± 4.6(P = 0.00007).CONCLUSION:The change in serotonin cells could be caused by an interaction between immune cells and serotonin cells,and that of PYY density might be secondary. AIM: To investigate colonic endocrine cells in lymphocytic colitis (LC) patients. METHODS: Fifty-seven patients with LC were included. These patients were 41 females and 16 males, with an average age of 49 years (range 19-84 years). Twenty-seven subjects that underwent colonoscopy with biopsies were used as controls. The subjects underwent colonoscopy because of gastrointestinal bleeding or health worries, where the source of bleeding was identified as haemorrhoids or angiodysplasia. They were 19 females and 8 males with an average age of 49 years (range 18-67 years). Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy. Biopsies were fixed in 4% buffered paraformaldehyde, embedded in paraffin and cut into 5 m-thick sections. immunostained by the avidin-biotin-complex method for serotonin, peptide YY (PYY), pancreatic polypeptide (PP) enteroglucagon and somatostatin cells. The cell densities were quantified by computerized image analysis usi ng Olympus software .RESULTS: The colon of both the patient and the control subjects were macroscopically normal. Histopathological examination of colon biopsies from controls revealed normal histology. All patients fulfilled the diagnosis criteria required for of LC: an increase in intraepithelial lymphocytes (> 20 lymphocytes / 100 epithelial cells) and surface epithelial damage with increased lamina propria plasma cells and absent or minimal crypt architectural distribution. In the colon of both patients and control subjects, serotonin-, PYY-, PP-, enteroglucagon-and somatostatin-immunoreactive cells were was located in the upper part of the crypts of Lieberkühn.These cells were basket-or flask-shaped. where was no statistically significant difference between the right and left colon in controls with regards to the densities of serotonin-and PYYimmunoreactive cells (P = 0.9 and 0.1, respectively) .Serotonin cell density in the right colon in controls was 28.9 ± 1.8 and in LC patients 41.6 ± 2.The left colon, the corresponding figures were 28.5 ± 1.9 and 42.4 ± 2.9, respectively (P = 0.009) .PYY cell density in the right colon of the controls was 10.1 ± 1 and of LC patients 41 In the left colon, PYY cell density in controls was 6.6 ± 1.2 and in LC patients 53.3 ± 4.6 (P = 0.00007). CONCLUSION: The change in serotonin cells could be caused by an interaction between immune cells and serotonin cells, and that of PYY density might be secondary.