MIB-1 as a predictor of response in lung allografts with moderate acute cellular rejection

Quantitation of T lymphocytes in posttransplant transbronchial biopsies

The diagnostic role of immunohistochemical staining for T lymphocytes in grading acute airway rejection has not been fully explored. We examined 136 transbronchial biopsies from 52 lung transplant patients and 9 nontransplant controls. Transplant rejection was based on histologic assessment of perivascular (A) and bronchiolar (B) infiltrates. The clinical indication for the 136 allograft biopsies was routine surveillance (n = 72), decreased pulmonary function, rule out rejection (n = 36), suspect infection (n = 16), rule out obliterative bronchiolitis (n = 6), and persistent postoperative graft failure (n = 6). T lymphocytes were counted in bronchial mucosa per 100 bronchial epithelial cells, and in alveolar walls per square millimeters, after immunohistochemical staining with anti-CD3, CD4, and CD8. In controls, the mean alveolar wall CD3 cell count was 45 per square millimeter (95% confidence intervals, 30-52 per square millimeter) and the mean CD8 count was 15 per square millimeter (2-20 per square millimeter). In surveillance and negative patient biopsies, alveolar wall CD8 counts were significantly greater than controls (P = .03 and .02, respectively). Mean alveolar wall CD3 counts were significantly higher in type A rejection (88.7 +/- 12.9) than controls and negative biopsies (42 +/- 5.3, P < .001), but there was no difference compared to infections (119.7 +/- 22, P > .5). Mucosal CD3 cell counts were significantly higher in type B rejection (16.1 +/- 2.5) than controls and negative biopsies (1.5 +/- 0.4, P < .001), and also higher than infections (3.9 +/- 1.1, P < .001). In 7% of biopsies, T-cell staining identified perivascular circumferential infiltrates that were difficult to identify on routine stains, and in an additional 9% minor changes in grading were made after reviewing T-cell markers. Immunohistochemical staining may help in identifying perivascular infiltrates and demonstrates increased intraepithelial T-cells even in low-grade type B rejection. Type B rejection as assessed quantitatively is more specific than type A rejection in comparison to infection.

Lymphoid cell proliferation in renal transplants: biologic and diagnostic implications

It is unclear whether alloreaction develops in peripheral lymphoid organs and effector cells being recruited to the target organs, or the entire process of alloreaction can happen within the transplanted kidneys. Interstitial inflammatory cell (IIC) proliferation was evaluated by MIB-1 antigen immunostain and the rate expressed as positive cells/1000 cells. This rate was higher in acute cell-mediated rejection (ACR) (25.7, n = 14) compared with normal kidney (0.4, n = 8), acute tubular necrosis (1.2, n = 8), chronic allograft nephropathy (CAN, 2.4, n = 20), and native kidneys with diverse diseases (9.2, n = 63); but was comparable to that in CAN with significant IIC (20.6, n = 16). 10.1% and 8.3% of T lymphocytes underwent proliferation in ACR with or without CAN, whereas only rare B lymphocytes or macrophages showed this change (<1.2%), regardless of diagnostic categories. All biopsies diagnosed as ACR in conjunction with a high rate of MIB-1 + IIC and 9/12 biopsies with CAN and significant IIC in which ACR was diagnosed due to a high rate of MIB-1 + IIC, responded to anti-rejection therapy. Proliferation of IIC involves predominantly T lymphocytes. These observations provide support for the concept of in situ alloimmunization, and facilitate the diagnosis of ACR.

Immunohistochemical staining for proliferation antigen as a predictor of chronic graft dysfunction and renal graft loss

BACKGROUND

Assessment of proliferation rate (PR%) using monoclonal antibody for Ki-67 antigen has recently been found to have prognostic importance in lung and cardiac allografts. We ascertained whether the same might be true for renal allografts.

METHODS

Newly cut sections from 20 archival paraffin blocks of renal allograft biopsy material showing acute cellular rejection and/or acute tubular necrosis (ATN) and absence of other pathology were stained using MIB-1 antibody and were further double-stained with anti-CD3, anti-CD20 or anti-CD68 antibodies. Counts of staining of mononuclear interstitial cells were correlated with clinical and pathological data.

RESULTS

Mean PR% was significantly greater than that in control renal allografts (13.23 +/- 1.94 vs. 2.84 +/- 1.66, p < 0.01). PR% of cases with ATN and no or borderline rejection was significantly lower than that of the remaining cases with acute rejection pathology (6.68 +/- 1.15 vs. 14.31 +/- 1.62, p < 0.05). However, PR% was neither correlated to histological rejection grade nor to long-term graft outcome. Double labelling failed to identify the cell type of most infiltrating MIB-1 positive cells.

CONCLUSIONS

Positive MIB-1 staining helps to identify the presence of rejection but does not appear to predict prognosis or correlate with the Banff classification of rejection pathology.

Sauropus androgynus-constrictive obliterative bronchitis/bronchiolitis--histopathological study of pneumonectomy and biopsy specimens with emphasis on the inflammatory process and disease progression

AIMS

The histopathology of the Sauropus androgynus (SA)-constrictive bronchiolitis obliterans (BO) is still controversial. A recent report using pneumonectomy specimens showed that the major histopathology was obliterative arteriopathy with segmental necrosis of small bronchi instead of constrictive BO as previously described.

METHODS AND RESULTS

We analysed semiquantitatively and immunohistochemically the histopathology of one pneumonectomy and four biopsies specimens of SA-associated lung disease. We found a significant number of constrictive and obliterative bronchioles 1 mm or less in diameter and segmental inflammatory destruction with complete luminal obliteration of the bronchi less than 3 mm in diameter in the pneumonectomy specimen (37% and 25%, respectively). Fibromuscular intimal sclerosis of the bronchial arteries was identified in 15% of the bronchi 4 mm or less in diameter. The inflammation in these airways was composed predominantly of T-lymphocytes, macrophages, mast cells and eosinophils. They were present throughout the evolutionary stages of the bronchiolitis ranging from early oedematous to the late fibrotic obliterative stage. Double immunohistochemical stains revealed negative proliferative cell nuclear antigen for most of the T-lymphocytes and macrophages but positive for fibroblasts.

CONCLUSIONS

A more accurate histopathological designation of the SA-associated lung disease should be constrictive obliterative bronchitis/bronchiolitis, with the participation of T-lymphocytes, macrophages, mast cells, eosinophils and fibroblasts in its morphogenesis. The persistent accumulation of inflammatory cells was mediated predominantly by continued recruitment to the site of injury from the bloodstream, resulting eventually in the irreversible fibrosis of the bronchioles and the bronchi less than 3 mm in diameter. Obliterative arteriopathy is suspected of being only an indirect contributing factor.