Induction of intestinal lesions in nu/nu mice induced by transfer of lymphocytes from syngeneic mice infected with murine retrovirus

Abstract

Background: Murine leukemia virus, LP-BM5, induces severe immunodeficiency with abnormal lymphoproliferation in susceptible C57BL/6 mice. In a previous study, it was shown that a Sjögren's syndrome-like systemic exocrinopathy is induced in the virus infected mice.

Aims: To examine lymphocyte functions of the virus infected mice.

Methods: Four-week old mice were inoculated with the virus and their spleen cells were transferred into syngeneic nu/nu mice. Their organs were examined by light and electron microscopy. Phenotypes of the colon infiltrating cells were examined by flow cytometry.

Results: All nu/nu recipients had died by six weeks after cell transfer, showing runting disease like cachexia with diarrhoea and anal bleeding. Histopathological examination revealed that systemic exocrinopathy was adoptively transferable and that the colon became thickened due to mononuclear cell infiltration into the mucosal and submucosal layer with hyperplasia of intestinal epithelial cells. No virus particles were found in the colon. Flow cytometric analyses revealed that most of the infiltrating CD4+ T cells showed CD45RBlow. No intestinal lesions were observed in the virus infected mice nor in nu/nu mice inoculated with normal lymphocytes.

Conclusion: Lymphocytes of the virus infected mice induced colitis and hyperplasia of intestinal epithelial cells as well as systemic exocrinopathy in nu/nu mice. Our experimental system may give some insight into intestinal lesions associated with virus infection.

Figure 1

: Flow cytometric analyses of spleen cells. A and C: spleen cells of mice infected with LP-BM5 eight weeks previously; B and D: untreated B6 spleen cells. Spleen cells were doubly stained with either FITC-anti-CD3 and PE-anti-B220 (A,B) or FITC-anti-CD4 and PE-anti-CD8 (C,D).

Figure 2

: Survival rate of B6 nu/nu mice inoculated with MAIDS spleen cells and control groups of mice. A: B6 nu/nu mice inoculated with MAIDS spleen cells; B: B6 nu/nu mice inoculated with untreated B6 spleen cells; C: B6 nu/nu mice infected with LP-BM5; D: untreated B6 nu/nu mice. Seven mice were used in each group and data were collected from two or three repeated experiments.

Figure 3

: Runting disease-like appearance of B6 nu/nu mice. A: gross appearance of a nu/nu mouse which received MAIDS spleen cells compared with B6 nu/nu mice which received syngeneic spleen cells; B: typical hunchback of a nu/nu mouse which received MAIDS spleen cells; C: mouse which shows anal prolapse and anal bleeding.

Figure 4

: Sjögren's syndrome-like exocrinopathy in B6 nu/nu mice inoculated with MAIDS spleen cells. A-C: Sjögren's syndrome-like exocrinopathy in salivary gland (A), lacrimal gland (B), and pancreas (C); D-I: controls; no pathological lesions are observed in these organs of nu/nu mice inoculated with untreated B6 spleen cells (D, salivary gland; E, lacrimal gland; F, pancreas) nor in uninoculated mice (G, salivary gland; H, lacrimal gland; I, pancreas). (Haematoxylin and eosin; original magnification: ×160.)

Figure 5

: Occurrence of severe colitis in B6 nu/nu mice inoculated with MAIDS spleen cells. A,B: B6 nu/nu mice inoculated with MAIDS spleen cells. Colitis with thickened walls and hyperplasia of the epithelial cells are observed; C-H: controls; colons of B6 nu/nu mice inoculated with B6 spleen cells (C,D), those of untreated B6 nu/nu mice (E,F), and B6 nu/nu mice infected with LP-BM5 (G,H). (Haematoxylin and eosin; original magnifications: A,C,E,G: ×16; B,D,F,H: ×160.)

Figure 6

: Occurrence of intestinal lesions in B6 nu/nu mice inoculated with MAIDS spleen cells. A: thickened intestinal wall in B6 nu/nu mice inoculated with MAIDS spleen cells. Cellular infiltration is localised in the lamina propria and submucosa of the small intestine. Epithelial cell hyperplasia is also observed but neither erosion nor ulcer is observed; B-D: controls; small intestines of B6 nu/nu mice inoculated with B6 spleen cells (B), untreated B6 nu/nu mice (C), and B6 nu/nu mice infected with LP-BM5 (D). (Haematoxylin and eosin; original magnification: ×120.)

Figure 7

: Electron microscopy findings of colitis in a B6 nu/nu mouse inoculated with MAIDS spleen cells. Colonic epithelial cells are injured by infiltrating lymphocytes, macrophages, and neutrophils. No virus particles are detected. Original magnification: ×3000. E, epithelial cells; G, goblet cells; L, lymphocyte; NP, neutrophil.

Figure 8

: Flow cytometry analyses of iIEL and LPL of colon of B6 nu/nu mice inoculated with MAIDS spleen cells. iIEL and LPL of B6 nu/nu mice inoculated with either MAIDS or untreated B6 spleen cells were stained with the following fluorescent dye labelled antibodies: A: FITC- anti-CD3 and PE-anti-B220; B: FITC-anti-CD4 and PE-anti-CD8; C: PE-anti-CD4 and FITC-anti-CD45RB.