Immunological Investigation Immunoglobulins Complement Flow Cytometry

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Immunological investigation is the laboratory complement to the clinical assessment of patients with suspected autoimmune, immunodeficiency, lymphoproliferative, or systemic inflammatory disease. The four pillars are: quantitation of immunoglobulins (IgG, IgA, IgM, IgE, and IgG subclasses), measurement of complement (C3, C4, CH50, AH50) and split products (C3d, C5a), phenotyping of peripheral blood lymphocytes by flow cytometry, and functional assays (lymphocyte proliferation, neutrophil oxidative burst, complement haemolytic activity). Each result has to be interpreted in the clinical context, and the FRACP candidate must be able to defend the choice, the limitations, and the interpretation of each test. ^{[1] [10]}

The consultant-level decision sequence is: (1) define the clinical syndrome (recurrent infection, autoimmunity, lymphadenopathy, vasculitis, immunodeficiency); (2) choose the laboratory test that discriminates the likely diagnoses; (3) interpret the result with attention to age-related reference ranges, analytical interferences, and the pre-analytical phase (sample handling, transport); and (4) integrate the laboratory picture with the clinical and histological findings before assigning a diagnosis or beginning treatment. ^{[9] [10]}

References10ShowHide

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