Single Antigen Bead Class II

What is Single Antigen Bead (SAB) Class II test?

The SAB Class II test is a highly sensitive, bead-based HLA antibody assay that detects and identifies IgG antibodies directed against specific HLA Class II antigens (HLA‑DR, ‑DQ, ‑DP) in serum, reporting signal strength as mean fluorescence intensity (MFI) for each single antigen bead. By coating each bead with a single recombinant Class II HLA antigen, the test provides allele-level specificity, enabling precise identification of class II donor‑specific antibodies (DSA) and comprehensive sensitization profiles.

Why consider Single Antigen Bead (SAB) Class II test?

• Pre‑transplant risk assessment: Detects and specifies Class II HLA antibodies to predict compatibility, support virtual crossmatch, and guide donor selection and immunosuppression to reduce antibody‑mediated rejection (AMR) risk.
• Post‑transplant monitoring: Tracks emergence or rise of Class II DSA, which are closely linked to AMR and graft injury; class II antibodies can be particularly persistent and clinically significant.
• Clarifying complex cases: Resolves specificity when screening/flow assays are positive or equivocal; SAB offers the highest resolution for defining exact antibody targets and avoiding false-positive interpretations from other methods.
• Therapeutic guidance: Semi‑quantitative MFI trends aid desensitization planning and monitoring response to therapies (e.g., plasmapheresis, IVIG, rituximab) before or after transplantation.

Who should get this Single Antigen Bead (SAB) Class II test?

• Solid‑organ transplant candidates (e.g., kidney, heart, lung, liver) for baseline sensitization mapping, especially with prior transplants, transfusions, or pregnancies that elevate HLA antibody risk.
• Recipients with suspected AMR or unexplained graft dysfunction to evaluate for de novo or rising Class II DSA.
• Patients with positive HLA antibody screening/flow crossmatch needing precise Class II specificity to perform an accurate virtual crossmatch and refine compatibility decisions.

More Information Single Antigen Bead (SAB) Class II test

Other names: SAB, Single Antigen Bead, Solid Organ Transplant, Kidney Transplant

A kidney transplant is surgery to place a healthy kidney from a donor into someone whose kidneys have failed. One working kidney can do the job of two, so only a single donor kidney is transplanted. Kidney transplantation involves assessing the recipient's overall health, ensuring a suitable donor match, and monitoring for complications post-transplant. This includes evaluating kidney function, matching tissue types (HLA typing), and assessing for antibodies that could cause rejection.