Interferon-␥ receptor ligand-binding chain (IFN-␥

To reduce the morbidity associated with CVID, there needs to be greater awareness of respiratory complications, particularly amongst physicians caring for such patients. Emphasis has been placed on adequate dosage of immunoglobulin, but early involvement by a respiratory physician is essential to monitor lung function and initiate optimal therapy, to minimize the occurrence and progression of lung damage.

Each of the four human IgG subclasses exhibits a unique profile of effector functions relevant to the clearance and elimination of infecting microorganisms. The quantitative response within each IgG subclass varies with the nature of the antigen, its route of entry and, presumably, the form in which it is presented to the immune system. This results in antibody responses to certain antigens being predominantly or exclusively of a single IgG subclass. An inability to produce antibody of the optimally protective isotype can result in a selective immunodeficiency state. This is particularly apparent for responses to certain bacterial carbohydrate antigens that are normally of IgG2 isotype. A failure to produce the appropriate specific antibody response may result in recurrent upper and/or lower respiratory tract infection. Careful patient investigation can identify such deficiencies and suggest appropriate clinical management. In this review we outline the biology and clinical relevance of the IgG subclasses and summarize current rational treatment approaches.

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