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Acute cellular rejection occurs early or late after renal transplantation when T-lymphocytes from the recipient directly attack and destroy cells in the transplanted kidney. This is the most common type of rejection and is also known as T-cell mediated rejection. Acute cellular rejection is usually suspected because of elevated serum creatinine. Elevated creatinine is also seen with infection and mechanical blockage. A “for-cause” biopsy is needed to confirm rejection. Up to half of “for-cause” biopsies may not show rejection. Acute cellular rejection can also occur without causing an elevation in serum creatinine, especially if immunosuppression is suboptimal. Surveillance biopsies are performed at predetermined intervals to detect this type of ‘silent’ rejection and assess immunosuppression.

The PleximarkTM blood test measures the likelihood of acute cellular rejection by measuring whether recipient lymphocytes called T-cytotoxic memory cells show increased anti-donor activity.

The PleximarkTM blood test measures the likelihood of acute cellular rejection by measuring whether recipient lymphocytes called T-cytotoxic memory cells show increased anti-donor activity. This activity is measured after stimulating lymphocytes from the recipient with donor or donor-like cells. To determine whether anti-donor activity is increased or decreased, it is compared with activity toward non-donor (reference) cells. Knowledge about the likelihood of acute cellular rejection can be combined with clinical information to develop a treatment plan by:

  • Assessing whether elevated serum creatinine indicates an increased likelihood of acute cellular rejection.
  • Assessing the adequacy of immunosuppression with serial use.
  • Optimizing the frequency of surveillance biopsies.

 

# CATEGORY DETAILS

1

Assay Category

Lab-developed test, antigen-specific T-cell function.

2

Intended Use

To measure the likelihood of Acute cellular rejection after Renal Transplantation.

3

Methodology

Stimulation of peripheral blood leukocytes with donor and non-donor cells, Flow Cytometry.

4

Test Report

Available within 30 hours of receiving a blood sample.

5

Test Readout

Index of Rejection (IR), the IR is the ratio of the recipient T-cytotoxic memory cell activity toward donor or donor-like cells and reference cells.

6

Reference Range

The IR is an absolute number with a range of less than 1.15 to 1.15 or greater.

7

Test Interpretation

An IR of 1.15 or more indicates an increased likelihood of acute cellular rejection.

Purpose

Knowledge about the risk of rejection can be combined with available clinical data to plan additional treatment for your patient. 

Rationale

  • Renal transplant rejection is usually suspected because of elevated serum creatinine. Elevated creatinine is also seen with infection and mechanical blockage. A “for-cause” biopsy is needed to confirm rejection. Roughly half of “for-cause” biopsies do not show rejection.
  • Rejection can also occur without affecting serum creatinine, especially if immunosuppression is suboptimal. Surveillance biopsies are performed at predetermined intervals to detect ‘silent’ rejection and assess immunosuppression.
  • The PleximarkTM blood test measures the likelihood of rejection. This knowledge can be combined with clinical information to develop a treatment plan. Benefits include:
    • Enhancing the diagnostic yield of “for-cause’ biopsies.
    • Optimizing the frequency of surveillance biopsies.
    • Improving the long-term management of immunosuppression with serial use.

Intended Use

To assess the likelihood of acute cellular rejection after renal transplantation.

Procedure

  • PleximarkTM is a functional cell-based blood test which measures the immune response of recipient lymphocytes to donor lymphocytes in cell culture. The immune response is measured as cells that express an inflammatory marker, CD154. 
  • The test requires whole blood in sodium heparin tubes to be shipped at ambient temperature for overnight delivery to Plexision’s laboratory. Seven-10 mL whole blood samples are needed from adults, and 3-5 mL samples are needed from children.
  • Results are expressed as an index of rejection, which is a measure of the likelihood of rejection.
  • Results are reported the day after the blood sample is received at the laboratory. For blood samples shipped overnight to Plexision’s laboratory, results are reported within two days of obtaining the blood sample from the patient.
  • The technology underlying the Pleximark™ test has been evaluated in over 200 children with liver or intestine transplantation and adults with renal transplantation.2-4

Performance

The Pleximark™ test is performed in Plexision's CLIA- approved laboratory and

  • Has been evaluated in relationship to “for-cause” biopsies in renal transplant recipients.
  • Identifies renal transplant recipients experiencing rejection with sensitivity and specificity of 88% and 86% respectively.

Benefits

Determining whether rejection is likely is important in deciding: 

  • Whether the right amount of immunosuppression is being given.
  • Whether anti-rejection medications can be decreased or not. 
  • Whether additional tests are needed to confirm rejection. 

Knowledge about the likelihood of rejection from the PleximarkTM test can be combined with other clinical data by your healthcare provider to make clinical decisions.

Insurance Coverage

Plexision will bill the patient's insurance plan and work directly with the insurer for payment. Plexision will assist with the cost of  Pleximark™, if there is no insurance coverage. For additional information, call 1.855.753.9474 or email info@plexision.com

Samples & Handling

# CATEGORY DETAILS

1

Sample Type Whole blood collected in a sodium heparin (green-top) tube.

2

Volume 5 mL in children and 8 mL in adults.

3

Transport Conditions Ship priority overnight, at room temperature. The sample must get to Plexision within 30 hours of the phlebotomy.

4

Specimen Stability

30 hours at room temperature from the time of phlebotomy.

5

Sample Discard Criteria
  • Transport time more than 30 hours from phlebotomy.
  • Lithium heparin (green-top) tube or ACD (yellow-top) tube.
  • Clotted, hemolyzed, frozen, refrigerated, or broken vacutainer seal.

How to Order

# CATEGORY DETAILS

1

Test Brochure View and download the product brochure here.

2

Ordering Tests Please complete this form, print, and fax to 412-224-2776.

PleximarkTM is a blood test that helps your healthcare provider determine whether rejection is likely after renal transplantation.

Kidney transplant recipients of any age can benefit from the PleximarkTM test.

The PleximarkTM test must be ordered by your healthcare provider. The test requires a sample of blood of two teaspoons. This sample is to be shipped overnight to Plexision’s laboratory for analysis. Results are sent to your healthcare provider within a day of your sample arriving at the laboratory. Your healthcare provider will help you understand the results.

Results are ready within 30 hours after the laboratory receives the blood sample.

The PleximarkTM test determines whether the recipient's immune system is reacting excessively toward the transplanted organ. This type of immune response occurs during transplant rejection, and can be measured in a type of white blood cell. When present, this increased immune response tells your healthcare provider whether transplant rejection is likely or not.

The results are reported as an Index of Rejection (IR). An index less than 1.15 implies a decreased likelihood of rejection. An index of 1.15 or greater implies an increased likelihood of rejection.

Determining whether rejection is likely is important in deciding whether the amount of anti-rejection medications is enough, whether these anti-rejection medications can be decreased further, or whether additional tests are needed to confirm whether rejection is already present or not. Knowledge about the likelihood of rejection can be combined with other clinical data by your healthcare provider to make clinical decisions.

The PleximarkTM test must be ordered by your healthcare provider. The test requisition form is provided here. The completed form can be faxed to 412-224-2776. If there are any questions, please contact (855) PLE.XISION (753.9474) or 412-224-2504.

Plexision will bill your healthcare facility or your insurance plan as indicated on the requisition form. Plexision’s patient assistance plans will assist you with the cost of PleximarkTM if there is no insurance coverage.

1. Patent 8759016

2. Transplantation. 2011 Aug 27;92(4):433-8. PMID: 21747326

3. Transplantation. 2017 Jan; 101(1): 131–140. PMID: 26950712

4. Am J Transplant. 2009 Jan;9(1):179-91. PMID:18976293.

5. Surgery. 2009. Aug;146(2):166-73.PMID:19628070.

PleximarkTM is a lab-developed test, and is not FDA-approved.

 

About

Plexision develops cellular biomarkers for personalized diagnosis and drug development in solid organ transplantation and immunological disorders. We also pioneer in R&D projects centered on integrating biomarker targets in all phases of drug development, from preclinical to post-marketing. Plexision’s technology can be adapted to

  • - Assess disease risk for several immunological disorders.
  • - Predict the success of a drug for a specific patient.
  • - Develop dosing recommendations for new immunological drugs.

Our state-of-the-art laboratory is CLIA-certified and located in Pittsburgh, PA.

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