Antigentyping

Antigentyping is a set of laboratory methods used to determine which antigens are present on cells, tissues, or pathogens by detecting specific antigen-antibody interactions. It is distinct from genotyping, which analyzes genetic sequences to infer antigenic properties. Antigentyping encompasses serological, immunological, and molecular approaches.

In transfusion medicine, antigentyping identifies blood group antigens such as ABO and Rh and other clinically significant markers to ensure proper compatibility and minimize reactions. In organ and bone marrow transplantation, HLA typing characterizes human leukocyte antigen alleles to optimize donor-recipient matching and graft survival. In microbiology, serotyping or antigen typing classifies strains by surface antigens (for example, bacterial O and K antigens) to track epidemiology and inform vaccine design. In research, antigentyping is used to define cell surface markers and to characterize cell lines or tissue samples.

Common techniques include serological assays that detect antigen-antibody agglutination or precipitation, flow cytometry with fluorescently labeled antibodies to quantify antigen expression, and immunoassays such as ELISA or Western blot. Molecular methods, including PCR-based or sequencing-based HLA typing, infer antigenic profiles from genetic information when direct antigen detection is impractical or limited.

Limitations include antigen variation, low expression levels, cross-reactivity of antibodies, need for well-characterized antisera, and cost or time constraints. Overall, antigentyping provides essential information for compatibility assessment, pathogen typing, and basic immunophenotyping in clinical and research settings.