HEp2

HEp-2, or human epithelial type 2, is a continuous cell line derived from a human laryngeal epidermoid carcinoma. It is one of the most widely used substrates in clinical immunology for screening antinuclear antibodies (ANA) by indirect immunofluorescence (IIF). The cell line's large, flat morphology and abundant nuclear and cytoplasmic antigens produce diverse fluorescence patterns that aid interpretation and patient stratification.

Origin and nomenclature: The line was established in the 1960s and has since become a standard reference material in many diagnostic laboratories. HEp-2 cells are grown on coated slides or in culture and fixed prior to use in ANA testing.

Clinical uses: In IIF assays, patient serum is applied to fixed HEp-2 cells, then a fluorescent secondary antibody is used to detect bound autoantibodies. The resulting staining patterns—nuclear (homogeneous, speckled, nucleolar), centromeric, and cytoplasmic—are read by trained personnel. Pattern recognition can suggest particular autoimmune diseases and guide confirmatory testing, though results must be interpreted in the clinical context.

Practical considerations: HEp-2 cells are supplied by cell banks and diagnostic suppliers and are used not only for ANA screening but also in research and development of immunoassays. Laboratories may optimize testing by using additional or alternative substrates to complement HEp-2-based screening.