CPT® Code 86052

The CPT® Code 86052 refers to the testing for Aquaporin-4 (AQP4) antibodies using a cell-based immunofluorescence assay (CBA). These antibodies serve as a highly specific and sensitive serological marker for neuromyelitis optica (NMO), which is an autoimmune disorder characterized by inflammation and demyelination within the central nervous system (CNS). NMO primarily impacts the optic nerves and spinal cord, but it can also affect the brain, leading to a range of severe symptoms. These symptoms may include vision loss, limb weakness or paralysis, uncontrollable vomiting or hiccups, painful muscle spasms, and dysfunction of the bladder or bowel. In pediatric patients, NMO can manifest as seizures or even coma. The presence of AQP4 antibodies is critical for differentiating NMO from multiple sclerosis (MS), as these antibodies are typically found in NMO but not in classical MS. The testing process involves collecting a venous blood sample from the patient, which is then analyzed using a cell-based indirect immunofluorescence assay (CIIFA) or cell-based indirect fluorescent antibody (CBA by IFA). This method utilizes human embryonic kidney (HEK) cells that have been genetically modified to express green fluorescent protein (GFP)-tagged AQP4, which are fixed onto slides and serve as the antigen substrate. The patient’s serum is incubated with these cells, followed by the addition of a secondary anti-human IgG antibody that is conjugated with fluorescein isothiocyanate. After the labeling process, the cells are washed and examined under a fluorescent microscope to detect the presence of AQP4 antibodies. The resulting fluorescent signal is scored qualitatively, and further titration studies may be conducted to determine the dilution factor at which the specific fluorescence can be identified, providing a semi-quantitative result. This test may be performed alongside other separately reportable tests to assist in confirming a diagnosis of NMO.