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Role of the thymus in transplantation tolerance in miniature swine. I. Requirement of the thymus for rapid and stable induction of tolerance to class I-mismatched renal allografts.

Yamada K, Gianello PR, Ierino FL, Lorf T, Shimizu A, Meehan S, Colvin RB, Sachs DH - J. Exp. Med. (1997)

Bottom Line: Thymectomized swine developed acute cellular rejection characterized by a T cell (CD25(+)) infiltrate, tubulitis, endothelialitis and glomerulitis, and anti-donor CTL reactivity in vitro.Nonthymectomized and sham thymectomized animals had a mild T cell infiltrate with few CD25(+) cells and no anti-donor CTL response in vitro.These results indicate that the thymus is required for rapid and stable induction of tolerance.

View Article: PubMed Central - PubMed

Affiliation: Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts, 02129, USA.

ABSTRACT
The almost uniform failure in transplant patients of tolerance-inducing regimens that have been found to be effective in rodents, has made it necessary to examine large animal models before testing of new approaches clinically. Miniature swine have been shown to share many relevant immunologic parameters with humans, and because of their reproducible genetics, have proved extremely useful in providing such a large animal model. We have previously shown that indefinite systemic tolerance to renal allografts in miniature swine is induced in 100% of cases across a two-haplotype class I plus minor histocompatibility antigen disparity by a 12-d course of Cyclosporine A (CyA), in contrast to irreversible rejection observed uniformly without CyA treatment. In the present study, we have examined the role of the thymus during the induction of tolerance by performing a complete thymectomy 21 d before renal transplantation. This analysis demonstrated a striking difference between thymectomized and nonthymectomized animals. Thymectomized swine developed acute cellular rejection characterized by a T cell (CD25(+)) infiltrate, tubulitis, endothelialitis and glomerulitis, and anti-donor CTL reactivity in vitro. Nonthymectomized and sham thymectomized animals had a mild T cell infiltrate with few CD25(+) cells and no anti-donor CTL response in vitro. These results indicate that the thymus is required for rapid and stable induction of tolerance.

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Representative histological findings of thymectomized animals and nonthymectomized animals. (a) A thymectomized animal on POD 8; diffuse and moderate mononuclear cell infiltration is seen with diffuse tubulitis. Glomeruli show typical acute allograft glomerulopathy (PAS ×200). (b) A  nonthymectomized animal on POD 8; mild and focal mononuclear cell infiltration is seen with mild focal tubulitis (PAS ×200). (c) Immunohistochemistry for CD25 on POD 8 in a thymectomized animal, and (d) a nonthymectomized animal. Many infiltrating mononuclear cells are seen expressing  CD25 in the thymectomized animal (c), whereas only a few of these cells are seen in nonthymectomized animal (d) (×600). (e) Thymectomized animal  on POD 60 shows chronic transplant glomerulopathy with diffuse interstitial fibrosis (PAS ×200), and (f) nonthymectomized animal show a normal  glomerular structure on POD 60 (PAS ×200).
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Figure 4: Representative histological findings of thymectomized animals and nonthymectomized animals. (a) A thymectomized animal on POD 8; diffuse and moderate mononuclear cell infiltration is seen with diffuse tubulitis. Glomeruli show typical acute allograft glomerulopathy (PAS ×200). (b) A nonthymectomized animal on POD 8; mild and focal mononuclear cell infiltration is seen with mild focal tubulitis (PAS ×200). (c) Immunohistochemistry for CD25 on POD 8 in a thymectomized animal, and (d) a nonthymectomized animal. Many infiltrating mononuclear cells are seen expressing CD25 in the thymectomized animal (c), whereas only a few of these cells are seen in nonthymectomized animal (d) (×600). (e) Thymectomized animal on POD 60 shows chronic transplant glomerulopathy with diffuse interstitial fibrosis (PAS ×200), and (f) nonthymectomized animal show a normal glomerular structure on POD 60 (PAS ×200).

Mentions: Serial kidney biopsies were performed on POD 8, 11, 18, 30, 60, and >100. Marked differences in histology were noted between thymectomized and nonthymectomized animals. Nonthymectomized animals and the sham-thymectomized controls demonstrated a patchy and mild mononuclear cell infiltrate with focal tubulitis between POD 8 and 18. Attachment of a few mononuclear cells to the endothelium in small arteries and glomerular capillaries was also observed (Fig. 4 b). The mononuclear cell infiltrate decreased by POD30, and remained minimal (<5% of the cortex) throughout the remainder of the experiment. In contrast, thymectomized animals showed acute cellular rejection, with a diffuse and marked mononuclear cell infiltration, tubulitis, and endothelialitis starting on POD 8 (Fig. 4 a). The glomeruli also showed a mononuclear cell infiltrate. By immunoperoxidase staining, both groups showed an infiltrate of CD4 and CD8 cells. However, many infiltrating cells expressed CD25 in the thymectomized animals (Fig. 4 c), whereas only a few infiltrating cells expressed CD25 in nonthymectomized animals, indicating more activation of infiltrating cells in thymectomized animals (Fig. 4 d). In late biopsies, the thymectomized animals developed chronic rejection, as manifested by allograft glomerulopathy, consisting of the duplication of glomerular basement membrane, marked mesangial proliferation, and segmental mesangial sclerosis, observed on POD 60 and 94 (Fig. 4 e). In addition, interstitial fibrosis and tubular atrophy were present. The glomerular changes correlated with proteinuria and weight loss in the thymectomized animals, and were not seen in nonthymectomized animals or the sham-thymectomized controls (Fig. 4 f  ).


Role of the thymus in transplantation tolerance in miniature swine. I. Requirement of the thymus for rapid and stable induction of tolerance to class I-mismatched renal allografts.

Yamada K, Gianello PR, Ierino FL, Lorf T, Shimizu A, Meehan S, Colvin RB, Sachs DH - J. Exp. Med. (1997)

Representative histological findings of thymectomized animals and nonthymectomized animals. (a) A thymectomized animal on POD 8; diffuse and moderate mononuclear cell infiltration is seen with diffuse tubulitis. Glomeruli show typical acute allograft glomerulopathy (PAS ×200). (b) A  nonthymectomized animal on POD 8; mild and focal mononuclear cell infiltration is seen with mild focal tubulitis (PAS ×200). (c) Immunohistochemistry for CD25 on POD 8 in a thymectomized animal, and (d) a nonthymectomized animal. Many infiltrating mononuclear cells are seen expressing  CD25 in the thymectomized animal (c), whereas only a few of these cells are seen in nonthymectomized animal (d) (×600). (e) Thymectomized animal  on POD 60 shows chronic transplant glomerulopathy with diffuse interstitial fibrosis (PAS ×200), and (f) nonthymectomized animal show a normal  glomerular structure on POD 60 (PAS ×200).
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Figure 4: Representative histological findings of thymectomized animals and nonthymectomized animals. (a) A thymectomized animal on POD 8; diffuse and moderate mononuclear cell infiltration is seen with diffuse tubulitis. Glomeruli show typical acute allograft glomerulopathy (PAS ×200). (b) A nonthymectomized animal on POD 8; mild and focal mononuclear cell infiltration is seen with mild focal tubulitis (PAS ×200). (c) Immunohistochemistry for CD25 on POD 8 in a thymectomized animal, and (d) a nonthymectomized animal. Many infiltrating mononuclear cells are seen expressing CD25 in the thymectomized animal (c), whereas only a few of these cells are seen in nonthymectomized animal (d) (×600). (e) Thymectomized animal on POD 60 shows chronic transplant glomerulopathy with diffuse interstitial fibrosis (PAS ×200), and (f) nonthymectomized animal show a normal glomerular structure on POD 60 (PAS ×200).
Mentions: Serial kidney biopsies were performed on POD 8, 11, 18, 30, 60, and >100. Marked differences in histology were noted between thymectomized and nonthymectomized animals. Nonthymectomized animals and the sham-thymectomized controls demonstrated a patchy and mild mononuclear cell infiltrate with focal tubulitis between POD 8 and 18. Attachment of a few mononuclear cells to the endothelium in small arteries and glomerular capillaries was also observed (Fig. 4 b). The mononuclear cell infiltrate decreased by POD30, and remained minimal (<5% of the cortex) throughout the remainder of the experiment. In contrast, thymectomized animals showed acute cellular rejection, with a diffuse and marked mononuclear cell infiltration, tubulitis, and endothelialitis starting on POD 8 (Fig. 4 a). The glomeruli also showed a mononuclear cell infiltrate. By immunoperoxidase staining, both groups showed an infiltrate of CD4 and CD8 cells. However, many infiltrating cells expressed CD25 in the thymectomized animals (Fig. 4 c), whereas only a few infiltrating cells expressed CD25 in nonthymectomized animals, indicating more activation of infiltrating cells in thymectomized animals (Fig. 4 d). In late biopsies, the thymectomized animals developed chronic rejection, as manifested by allograft glomerulopathy, consisting of the duplication of glomerular basement membrane, marked mesangial proliferation, and segmental mesangial sclerosis, observed on POD 60 and 94 (Fig. 4 e). In addition, interstitial fibrosis and tubular atrophy were present. The glomerular changes correlated with proteinuria and weight loss in the thymectomized animals, and were not seen in nonthymectomized animals or the sham-thymectomized controls (Fig. 4 f  ).

Bottom Line: Thymectomized swine developed acute cellular rejection characterized by a T cell (CD25(+)) infiltrate, tubulitis, endothelialitis and glomerulitis, and anti-donor CTL reactivity in vitro.Nonthymectomized and sham thymectomized animals had a mild T cell infiltrate with few CD25(+) cells and no anti-donor CTL response in vitro.These results indicate that the thymus is required for rapid and stable induction of tolerance.

View Article: PubMed Central - PubMed

Affiliation: Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts, 02129, USA.

ABSTRACT
The almost uniform failure in transplant patients of tolerance-inducing regimens that have been found to be effective in rodents, has made it necessary to examine large animal models before testing of new approaches clinically. Miniature swine have been shown to share many relevant immunologic parameters with humans, and because of their reproducible genetics, have proved extremely useful in providing such a large animal model. We have previously shown that indefinite systemic tolerance to renal allografts in miniature swine is induced in 100% of cases across a two-haplotype class I plus minor histocompatibility antigen disparity by a 12-d course of Cyclosporine A (CyA), in contrast to irreversible rejection observed uniformly without CyA treatment. In the present study, we have examined the role of the thymus during the induction of tolerance by performing a complete thymectomy 21 d before renal transplantation. This analysis demonstrated a striking difference between thymectomized and nonthymectomized animals. Thymectomized swine developed acute cellular rejection characterized by a T cell (CD25(+)) infiltrate, tubulitis, endothelialitis and glomerulitis, and anti-donor CTL reactivity in vitro. Nonthymectomized and sham thymectomized animals had a mild T cell infiltrate with few CD25(+) cells and no anti-donor CTL response in vitro. These results indicate that the thymus is required for rapid and stable induction of tolerance.

Show MeSH
Related in: MedlinePlus