T lymphocyte subsets and activation status in patients following liver transplantation

Multiplex Immunofluorescence for Detection of Spatial Distributions of Infiltrating T Cells Within Different Regions of Hepatic Lobules During Liver Transplantation Rejection

It remains unclear as to whether there are differences that exist in the types and functional status of immune cells within different areas of the liver lobules after rejection of liver transplantation. The composition of infiltrating T cells in liver allografts during liver transplantation rejection is indistinct and difficult to visualize within the same biopsy slide. In an attempt to rectify this problem, we applied multiplex immunofluorescent assays to assess the spatial distribution of various types of infiltrating T cells in different areas of the liver lobules after liver transplantation. In identical areas of the hepatic lobules, the percentage of CD4⁺ T, CD8⁺ T, and regulatory T (Treg) cells in the rejection group was greater than that observed in the non-rejection and normal groups. Within all three groups, the percentage of CD4⁺ T, CD8⁺ T, and Treg cells from the periportal to perivenous zones initially increased and then decreased. In the rejection group, the percentage of CD8⁺ T cells gradually increased from the periportal to perivenous zones, with maximal levels in the perivenous as compared with that in the transitional and periportal zones. In conclusion, levels of CD8⁺ T cells within different regions of liver lobules are closely related to levels of rejection after liver transplantation. Liver transplantation rejection may be linked with increases in CD8⁺ T cells within the perivenous zone. Although the regional percent of increase in CD4⁺ T cells may not reflect level of the rejection, the overall numbers of both of CD4⁺ and CD8⁺ T cells within different regions were closely related to rejection levels.

T-Cell Surface Antigens and sCD30 as Biomarkers of the Risk of Rejection in Solid Organ Transplantation

T-cell activation is a characteristic of organ rejection. T cells, located in the draining lymph nodes of the transplant recipient, are faced with non-self-molecules presented by antigen presenting cells and become activated. Activated T cells are characterized by up-regulated surface antigens, such as costimulatory molecules, adhesion molecules, chemokine receptors, and major histocompatibility complex class II molecules. Surface antigen expression can be followed by flow cytometry using monoclonal antibodies in either cell function assays using donor-specific or nonspecific stimulation of isolated cells or whole blood and without stimulation on circulating lymphocytes. Molecules such as CD30 can be proteolytically cleaved off the surface of activated cells in vivo, and the determination of the soluble protein (sCD30) in serum or plasma is performed by immunoassays. As promising biomarkers for rejection and long-term transplant outcome, CD28 (costimulatory receptor for CD80 and CD86), CD154 (CD40 ligand), and sCD30 (tumor necrosis factor receptor superfamily, member 8) have been identified. Whereas cell function assays are time-consuming laboratory-developed tests which are difficult to standardize, commercial assays are frequently available for soluble proteins. Therefore, more data from clinical trials have been published for sCD30 compared with the surface antigens on activated T cells. This short review summarizes the association between selected surface antigens and immunosuppression, and rejection in solid organ transplantation.

Lymphocyte surface molecules as immune activation biomarkers

Immunosuppression is mandatory after solid organ transplantation between HLA mismatched individuals. It is a lifelong therapy that needs to be closely monitored to avoid under- and over-immunosuppression. For many drugs, pharmacokinetic monitoring has been proven to be beneficial. However, the therapeutic ranges are statistically derived surrogate markers for the effects that cannot predict the individual response of single patients. Better tailored immunosuppression biomarkers are needed that indicate immune activation. T cells are critically involved in organ rejection, and the means to assess their activation state may be promising to individualize immunosuppressive therapies. Activated T cells can be monitored with flow cytometry based on surface molecules that are typically up regulated or with molecules that are cleaved off the cell surface. Among these molecules are the interleukin-2 receptor (CD25); transferrin receptor (CD71); the T cell co-stimulatory molecules CD28, CD69, and CD154 and sCD30, which is a member of the TNF-alpha family. The effect of immunosuppressive drugs on T cell activation can be recorded with indirect cell function assays or by directly monitoring activated T cells in whole blood. Soluble proteins can be measured with immunoassays. This review provides a summary of the experimental and clinical studies investigating the potential of surface molecules as a tool for immune monitoring. It critically discusses the obstacles and shortcomings from an analytical and diagnostic perspective that are currently preventing their use in multicenter trials and clinical routine monitoring of transplant patients.

Correlation between acute rejection severity and CD8-positive T cells in living related liver transplantation

The Banff schema is the most widely used standard grading system for liver allograft rejection. To investigate the relationship between the Banff rejection activity index (RAI) and the presence of lymphocyte subpopulations in allograft liver tissue, assuming these cells to probably play an important role in the mechanism of acute cellular rejection (ACR), we performed immunohistological examinations using liver tissues with various ACR severities after living related liver transplantation (LRLT). In total, 37 needle liver biopsy specimens with ACR in LRLT were examined using antibodies to CD4, CD8, and CD20. Formalin-fixed and paraffin-embedded liver tissues were used to maintain morphology. Immunohistological findings and RAI score according to the Banff schema were compared. In the results, mainly CD8-positive (CD8+), rather than CD4-positive (CD4+), cells were detected in the portal tract and were also found in bile duct epithelium and subendothelial areas of portal veins. The number of CD8+ cells increased according to ACR grade, whereas CD4+ cells tended to decrease. There were significant correlations between the presence of CD8+ cells (p = 0.0006) and CD4+ cells (p = 0.0003) and ACR severity. On the other hand, CD20-positive cells did not correlate with ACR severity (p = 0.472). The results indicate that CD8+ cells play important roles in ACR severity of LRLT, suggesting the number of CD8+ cells in liver tissue to be useful as a supplementary tool, in addition to RAI of the Banff schema, for objective evaluation of ACR severity.

Influence of pretransplant dialysis modality on the change of lymphocyte subset populations and acute rejection rates after renal transplantation

BACKGROUND

The influence of dialysis modality on the acute rejection (AR) rate after renal transplantation is controversial. We investigated whether the pretransplant dialysis modality correlated with the lymphocyte subset populations and the incidence of AR after renal transplantation.

METHODS

Thirty-eight first living renal transplant recipients, consisting of 22 patients on pretransplant hemodialysis (HD) and 16 patients on pretransplant peritoneal dialysis (PD), were studied. Peripheral blood samples were taken on days -1 through 28 after transplantation, and the lymphocyte fractions were exposed to the monoclonal antibodies anti-CD3, CD19, CD4, CD8 and CD28 for a flow cytometer analysis. Biopsy specimens were obtained at the time of presumed AR episodes and on day 28 after transplantation.

RESULTS

The PD patients had a higher frequency of AR (37.5% in PD vs 9.1% in HD patients, P = 0.034). In contrast, two HD patients showed graft loss at 18 and 30 months after transplantation. The increases of CD3, CD19, CD4 and CD4+ CD28+ cells in the PD patients occurred earlier than in the HD patients and the numbers of these cells in the PD group were higher than those in the HD between days 3-28 after transplantation, most significantly on day 7.

CONCLUSIONS

These findings suggest that the PD patients with similar clinical characteristics could potentially have a higher immunocompetence and immune responsiveness associated with a higher rate of AR in the early stage of renal transplantation when compared with the HD patients.