TL;DR: Aetna, a CVS Health company, modified CPB 0773 covering transplant immune cell function assays, effective January 5, 2026. CPT 86352 remains the only covered code — but the list of excluded tests just got longer, and your billing team needs to know exactly which assays are now explicitly off the table.
Aetna's transplant immune cell function assay coverage policy under CPB 0773 in the CPB 0773 Aetna system draws a sharp line between one covered use case and a growing list of experimental designations. The policy governs transplant immune cell function assay billing for CPT 86352, along with several proprietary tests billed under CPT codes 0118U, 0581U, and 81560 — all of which land in the "not covered" column. If your practice manages transplant patients or bills for post-transplant monitoring, this update demands a close look before January 5, 2026.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | Aetna, a CVS Health company |
| Policy | Transplant Immune Cell Function Assays |
| Policy Code | CPB 0773 |
| Change Type | Modified |
| Effective Date | January 5, 2026 |
| Impact Level | High |
| Specialties Affected | Transplant medicine, nephrology, pulmonology, rheumatology, gastroenterology, hematology/oncology |
| Key Action | Audit all ImmuKnow, Pleximmune, T-SPOT.CMV, and donor-derived cell-free DNA claims against updated criteria before January 5, 2026 |
Aetna Transplant Immune Cell Function Assay Coverage Criteria and Medical Necessity Requirements 2026
The Aetna transplant immune cell function assay coverage policy keeps CPT 86352 — the cellular function assay involving stimulation and biomarker detection — on the covered list. But the criteria are narrow. Medical necessity applies only to the ImmuKnow Assay (Cylex, Inc., Columbia, MD) when used to evaluate over-immunosuppression in transplant recipients who also have a co-morbid infection or cancer.
That's it. One assay, one manufacturer, two qualifying co-morbid conditions. The coverage policy does not extend to routine post-transplant monitoring, rejection surveillance, or CMV risk management in most contexts.
There is no mention of a prior authorization requirement specific to CPT 86352 in the updated policy text, but that doesn't mean your payer contracts are silent on it. Check your Aetna contract terms before assuming clean-claim submission. Reimbursement for CPT 86352 depends entirely on documenting the co-morbid infection or cancer with the right ICD-10 codes — the diagnosis pairing is what keeps this claim off the denial queue.
The medical necessity standard here is tighter than it sounds in practice. A transplant patient with stable labs who happens to have a URI doesn't automatically qualify. The policy targets adjudication of over-immunosuppression — meaning the clinical question should be whether to reduce immunosuppressive therapy. If that's not the documented clinical question, the claim is exposed.
Aetna Transplant Immune Cell Function Assay Exclusions and Non-Covered Indications
This is where the policy does most of its work — and where your claim denial risk lives.
Aetna labels nine specific ImmuKnow Assay uses as experimental, investigational, or unproven. That list includes CMV risk stratification in lung transplant recipients, cellular immune function detection in renal cell carcinoma patients, and rejection identification before kidney, liver, lung, or other solid organ transplants. If your transplant team has been ordering ImmuKnow for any of these purposes, those claims will not survive scrutiny under this policy.
The experimental list also covers management of allogeneic hematopoietic stem cell transplantation (CPT 38240 is listed as a related code but is not covered under this policy), inflammatory bowel diseases including Crohn's disease and ulcerative colitis, and prediction of infection risk in patients on disease-modifying anti-rheumatic drugs or those with lupus nephritis. These are common clinical scenarios. The coverage policy is unambiguous about all of them: not covered.
Beyond ImmuKnow, Aetna explicitly calls out several other proprietary tests as experimental for all indications:
| # | Excluded Procedure |
|---|---|
| 1 | Pleximmune (CPT 81560) — prediction of acute cellular rejection in pediatric liver or intestine transplant recipients, and every other use |
| 2 | T-SPOT.CMV — all indications |
| 3 | Gamma interferon response — measurement of immunosuppressive medication bioactivity in lung transplantation |
| 4 | Non-HLA autoantibody measurement (CPT 0581U) — biomarker for allograft rejection in solid organ transplantation |
| 5 | Donor-derived cell-free DNA (e.g., Viracor TRAC, CPT 0118U) — biomarker for allograft rejection in solid organ transplantation |
| 6 | CMV T Cell Immunity Panel — management post solid organ or hematopoietic stem cell transplantation |
| 7 | IFN-γ ELISpot assays (e.g., T-Track CMV) — evaluation of CMV-specific cellular immunity in immunocompromised patients |
| 8 | QuantiFERON-CMV — evaluation of congenital CMV infection and monitoring of autoimmune disease patients on immunosuppressants |
The donor-derived cell-free DNA exclusion is worth flagging separately. The Viracor TRAC assay has been gaining clinical traction in transplant medicine. Aetna's position here is clear — it's not covered under this policy regardless of clinical momentum.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| ImmuKnow Assay for over-immunosuppression — transplant recipients with co-morbid infection | Covered | CPT 86352 + infectious disease ICD-10 (A00.0–B99.9) | Medical necessity documentation required |
| ImmuKnow Assay for over-immunosuppression — transplant recipients with co-morbid cancer | Covered | CPT 86352 + malignant neoplasm ICD-10 (C00.0–C96.9) | Medical necessity documentation required |
| ImmuKnow for CMV risk stratification in lung transplant recipients | Experimental | CPT 86352 | Not covered under this policy |
| ImmuKnow for cellular immune function in renal cell carcinoma | Experimental | CPT 86352 | Not covered (malignant neoplasms exclusion C00.0–D09.9 for this use) |
| ImmuKnow for rejection risk identification — kidney, liver, lung, solid organ | Experimental | CPT 86352 | Not covered |
| ImmuKnow for allogeneic hematopoietic stem cell transplantation management | Experimental | CPT 86352, CPT 38240 | Not covered |
| ImmuKnow for inflammatory bowel disease (Crohn's, ulcerative colitis) | Experimental | CPT 86352 | Not covered |
| ImmuKnow for post solid organ transplant rejection management | Experimental | CPT 86352 | Not covered |
| ImmuKnow for post-surgical immune response monitoring | Experimental | CPT 86352 | Not covered |
| ImmuKnow for DMARD infection risk prediction | Experimental | CPT 86352 | Not covered |
| ImmuKnow for lupus nephritis infection risk prediction | Experimental | CPT 86352 | Not covered |
| Pleximmune — pediatric liver/intestine rejection prediction | Experimental | CPT 81560 | Not covered for any indication |
| T-SPOT.CMV — all indications | Experimental | — | Not covered |
| Gamma interferon response in lung transplant | Experimental | — | Not covered |
| Non-HLA autoantibody measurement | Experimental | CPT 0581U | Not covered |
| Donor-derived cell-free DNA (Viracor TRAC) | Experimental | CPT 0118U | Not covered for allograft rejection biomarker use |
| CMV T Cell Immunity Panel — solid organ or HSCT | Experimental | — | Not covered |
| IFN-γ ELISpot assays (T-Track CMV) | Experimental | — | Not covered |
| QuantiFERON-CMV | Experimental | — | Not covered |
Aetna Transplant Immune Cell Function Assay Billing Guidelines and Action Items 2026
| # | Action Item |
|---|---|
| 1 | Audit all open and pending CPT 86352 claims before January 5, 2026. Flag any claims where the documented indication falls outside the two covered use cases — over-immunosuppression with co-morbid infection or cancer. Pull the last 90 days of claims and cross-reference the ICD-10 codes. |
| 2 | Pull any submitted or upcoming claims for CPT 0118U, 0581U, and 81560 immediately. These codes appear in the policy under the experimental designation group. Any claim for these tests against Aetna is a denial waiting to happen. If your lab or ordering physicians have been using these assays, have a conversation with your medical director before the effective date. |
| 3 | Update your charge capture and order sets for the ImmuKnow Assay. If your transplant coordinators or physicians are ordering ImmuKnow for rejection surveillance or CMV risk management, the order set needs a hard stop or a coverage notice. Orders placed for non-covered indications will generate claims that will be denied. |
| 4 | Train ordering physicians on the narrow covered window. The covered use — adjudicating over-immunosuppression in patients with co-morbid infection or cancer — is specific. If the clinical question is "is this patient at risk for rejection," the answer from Aetna's billing standpoint is "not covered." Physicians need to understand this distinction before they sign the order. |
| 5 | Document the clinical question explicitly in the encounter note. For the one covered use case, your claim's defense depends on documentation showing the clinical team was evaluating whether to reduce immunosuppressive therapy in a patient with active infection or confirmed malignancy. Vague notes won't hold up on appeal. |
| 6 | Check your contracts for prior authorization requirements on CPT 86352. The policy text doesn't specify prior authorization, but individual Aetna plan contracts vary. Don't assume the policy silence means no prior auth is needed. Confirm with your Aetna provider relations contact or check your contract terms. |
| 7 | If you bill for pediatric transplant services and have used Pleximmune (CPT 81560), talk to your compliance officer now. Pleximmune is listed as experimental for all indications — including pediatric liver and intestine transplant rejection prediction. If you've been billing this test with an expectation of coverage, you need a retroactive claims review. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Transplant Immune Cell Function Assays Under CPB 0773
Covered CPT Codes (When Selection Criteria Are Met)
| Code | Type | Description |
|---|---|---|
| 86352 | CPT | Cellular function assay involving stimulation (e.g., mitogen or antigen) and detection of biomarker |
Not Covered / Experimental CPT Codes
| Code | Type | Description | Reason |
|---|---|---|---|
| 38240 | CPT | Hematopoietic progenitor cell (HPC); allogeneic transplantation per donor | Related code — listed as other CPT; ImmuKnow for HSCT management is experimental |
| 0118U | CPT | Transplantation medicine, quantification of donor-derived cell-free DNA using whole genome next-generation sequencing | Experimental — donor-derived cell-free DNA (e.g., Viracor TRAC) not covered as allograft rejection biomarker |
| 0581U | CPT | Autoantibody to Non-Human Leukocyte Antigen (non-HLA), Mayo Clinic Jacksonville, Mayo Clinic | Experimental — non-HLA autoantibody measurement not covered as allograft rejection biomarker |
| 81560 | CPT | Transplantation medicine (allograft rejection, pediatric liver and small bowel), measurement of donor and recipient HLA | Experimental — Pleximmune not covered for any indication |
Key ICD-10-CM Diagnosis Codes
The policy covers 562 ICD-10-CM codes in total. Below are the clinically significant codes most relevant to covered and non-covered billing scenarios.
| Code | Description |
|---|---|
| A00.0–B99.9 | Infectious and parasitic diseases (supports covered indication with CPT 86352) |
| B20 | Human immunodeficiency virus [HIV] disease |
| B25.8 | Other cytomegaloviral diseases (CMV risk stratification — listed but not a covered indication) |
| B59 | Pneumocystosis |
| B97.35 | Human immunodeficiency virus, type 2 [HIV-2] |
| C00.0–C96.9 | Malignant neoplasm (supports covered indication with CPT 86352) |
| C00.0–D09.9 | Malignant neoplasms — not covered for detection of cellular immune function in renal cell carcinoma |
| D47.z1 | Post-transplant lymphoproliferative disorder (PTLD) |
| D70.0–D77 | Other disorders of blood and blood-forming organs |
| D80.0–D89.9 | Certain disorders of the immune mechanism |
| D89.810–D89.813 | Graft-versus-host disease |
| E08.00–E13.9 | Diabetes mellitus |
| G35.A–G35.D | Multiple sclerosis |
| I12.0 | Hypertensive chronic kidney disease |
| I13.11 | Hypertensive heart and chronic kidney disease, stage 5 CKD |
| I13.2 | Hypertensive heart and chronic kidney disease with heart failure, stage 5 CKD |
The ICD-10 pairing is where this policy creates real claim denial exposure. Billing CPT 86352 with a rejection-surveillance diagnosis — rather than an active infection or confirmed cancer — will trigger a denial. The diagnosis code has to match the covered clinical question precisely.
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