What is an Immune-mediated Disease?

There is a spectrum of immune-mediated disease that may be considered on a number of different levels. Clinically, four major subtypes of immune system abnormality are recognized: 1) primary congenital immunodeficiency, 2) allergy, 3) autoimmunity, and 4) immune system neoplasia. On another level, immune-mediated disease might be considered to be primary or secondary in nature. Finally, many types of immune-mediated diseases might be considered mechanistically--using the Gel and Coombs classification of hypersensitivity reactions.

What are the General Characteristics of Immune-Mediated Disease?

 A strong genetic basis

 Particular age predispositions

 Non-specific clinical signs

 A waxing and waning clinical course

 Absence of underlying disease or recognized trigger factors

 Response to immunomodulatory therapy

What are the Laboratory Hallmarks of Immune-Mediated Disease?

 Many animals with immune-mediated disease will have serum polyclonal hypergammaglobulinaemia and elevation in serum concentrations of IgG, IgM or IgA.

 Leukocytosis, in particular neutrophilia, is often a hallmark of immune-mediated disease.

 Lymphadenopathy is a common feature of immune-mediated disease and is a reflection of immune system activation.

 All cats with suspected immune-mediated disease should be screened for retroviral infection (FeLV, FIV).

 The serological changes compatible with immune-mediated disease are often very specific for the disease process. By contrast, some serological changes are less disease specific

 The revolution in molecular diagnostics has ready applicability to diagnosis of immune-mediated disease.