Morphological and immunohistochemical studies of solitary lymphatic nodule (SLN) obtained by biopsy in normal human terminal ileum and duodenal bulb were performed. The size of SLN and the distribution of cells reacting with monoclonal antibodies to T cell subsets were examined. After fixation in peroxidase-lysin-4% paraform aldehyde (PLP), the specimens were washed in phosphate buffer solution (PBS), embeded in OCT-compound and sectioned into 4-6μm thickness on a cryostat. The size of lymphatic nodule and germinal center were measured under a light microscope using a micrometer. Immunohistochemical staining was performed by indirect peroxidase method using monoclonal antibodies (Leu series).
The results obtained were as follows.
1. The ratio of maximal diameter of germinal center/lymphatic nodule (GC/LN) of the elevated type SLN in duodenal bulb was higher than that of depressed type SLN in duodenal bulb and that of SLN in terminal ileum. No significant difference was found in the size of maximal diameter of the lymphatic nodule between them.
2. The incidences of Leu 1
+ cells and Leu 2a
+ cells were higher than that of Leu 3a
+ cells in the interepithelium covering lymphatic nodule of terminal ileum and duodenal bulb. The incidences of Leu 1
+ and Leu 3a
+ cells in the interepithelium of villi were similar to those in the interepithelium covering lymphatic nodule.
3. The incidences of Leu 1
+ cells and Leu 3a
+ cells were higher than that of Leu 2a
+ cells in SLN (germinal center and follicular area), and the incidence of Leu 1
+ cells was higher than that of Leu 2a
+ cells and Leu 3a
+ cells in the parafollicular area of terminal ileum. The incidences of Leu 1
+, Leu 2a
+ and Leu 3a
+ cells of SLN in duodenal bulb were similar to those in terminal ileum. In comparison between the terminal ileum and duodenal bulb, the incidences of Leu 1
+, Leu 2a
+ and Leu 3a
+ cells in the follicular area and that of Leu 3a
+ cells in the germinal center of duodenal bulb were higher than those of terminal ileum.
4. No significant difference was found in the incidence between Leu 2a
+ cells and Leu 3a
+ cells in the lamina propria (villous process and between crypts) of terminal ileum and duodenal bulb.
It is assumed that the structual difference of SLN in the terminal ileum and duodenal bulb presumably reflect the different immunological responces following the difference of the antigens in these areas.
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