Summary & Overview

CPT 86821: Lymphocyte Crossmatch for HLA Incompatibility

CPT code 86821 identifies a lymphocyte crossmatch assay used to detect human leukocyte antigen (HLA) incompatibility between transplant recipients and potential donors. This pre-transplant compatibility test is clinically significant because it helps predict risk of graft rejection and informs donor selection, affecting transplant outcomes and downstream costs. Nationally, accurate coding for such immunologic assays supports appropriate lab reimbursement and consistent clinical documentation.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The report provides readers with clinical context for the assay, typical sites of service, and the types of benchmarks and policy updates often relevant to laboratory immunology testing.

Readers will learn: the clinical purpose of the assay and where it is performed, common billing and coding considerations tied to laboratory services, how major payers approach coverage in general terms (Data not available in the input), and where to look for policy or reimbursement updates. Data gaps in the provided input are noted as "Data not available in the input," and specific payer policy details, taxonomies, and diagnosis crosswalks are not included here.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare86821CPTlymphocyte crossmatchHLA incompatibilitytransplant testinglaboratory immunologypre-transplant assessment

Billing Code Overview

CPT code 86821 describes a laboratory test in which a lab analyst cultures lymphocytes from a transplant recipient together with lymphocytes from a potential donor and observes for a cellular response that indicates human leukocyte antigen (HLA) incompatibility. This assay assesses immunologic compatibility between donor and recipient prior to transplantation.

Service type: Laboratory immunology compatibility testing
Typical site of service: Clinical laboratory or hospital laboratory setting

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Clinical & Coding Specifications

Clinical Context

A 45-year-old man with end-stage renal disease is evaluated for a living-related kidney transplant. The transplant coordinator schedules HLA compatibility testing between the intended donor (his sister) and the recipient. Blood samples are collected from both individuals and sent to the immunogenetics laboratory. The lab analyst performs a lymphocyte crossmatch (86821) by co-culturing recipient and donor lymphocytes and observing for a cytotoxic or proliferative response indicating HLA incompatibility. Results are reported to the transplant team to guide immunologic risk assessment and donor selection. Typical workflow steps include sample collection in referenced anticoagulant tubes, specimen accessioning, lymphocyte isolation, cultured crossmatch setup, incubation and monitoring, interpretation, and formal result reporting to the transplant surgeon and nephrology team.

Typical site of service: Hospital outpatient laboratory or hospital-based specialty immunogenetics laboratory. The service is usually ordered by transplant surgeons, nephrologists, or transplant coordinators prior to transplantation or when evaluating donor–recipient compatibility.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician or pathologist interpretation portion of a split-service test if the technical work (laboratory processing) is billed separately.

Taxonomy Code	Specialty	Notes
207L00000X	Clinical Laboratory	Clinical laboratory directors and analysts performing serologic and cellular immunology testing.
207K00000X	Immunology	Specialists in immunology or transplant immunology interpreting complex compatibility testing.
207RC0000X	Anatomic and Clinical Pathology	Pathologists who provide oversight and interpretation for laboratory-based crossmatch testing.

CPT Code	Description	Relationship to This Procedure
`86850`	Tissue typing; HLA additional typing, each locus	Performed to determine specific HLA alleles; often done before or in conjunction with crossmatch to assess compatibility.
`86816`	HLA antibody testing, class I or II, specificities detected by single antigen beads	Used to detect recipient anti-HLA antibodies that may predict crossmatch results and transplant risk.
`86825`	Lymphocytotoxic crossmatch, complement dependent, each test serum	An alternative crossmatch method (complement-dependent cytotoxicity) that may be performed alongside or instead of cultured lymphocyte methods.
`88360`	Immunohistochemistry, per specimen; initial single antibody stain	Used in transplant pathology when evaluating biopsy specimens post-transplant; related in the overall transplant testing pathway.
`36415`	Collection of venous blood by venipuncture	Common ancillary procedure required to obtain specimens for HLA crossmatch testing.

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