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Immunology: common variable immunodeficiency disorder
Synonym(s): CVID
Introduction
- The most commonly diagnosed primary immunodeficiency disease in the horse.
- Cause: a primary humoral immunodeficiency in which B-cells either fail to develop or to differentiate into antibody-secreting plasma cells, resulting in hypo- or agammaglobulinemia; possibly caused by multiple gene defects.
- Signs: recurrent fevers and bacterial infections.
- Diagnosis: clinical signs and laboratory results.
- Treatment: prolonged parenteral antibiotic therapy.
- Prognosis: grave, rarely living beyond six months from the time of diagnosis; repeat episodes of clinical disease are common; euthanasia is often requested.
Presenting signs
- Recurrent fevers and bacterial infections.
- Inappropriate response to tetanus toxoid vaccination Tetanus toxoid .
Acute presentation
- Ataxia.
- Seizures.
- Acute bacterial infections in various body systems.
Age predisposition
- Generally adults - between 2 and 19 years.
Breed/Species predisposition
- No breed or familial predisposition is recognized at present, although the possibility of genome abnormalities is currently under investigation.
Pathogenesis
Etiology
- A primary humoral immunodeficiency in which B-cells either fail to develop, or to differentiate into antibody-secreting plasma cells.
- In humans, multiple gene defects have been recognized and are thought to be the cause, although this has not yet been identified in horses, and is currently under investigation.
Pathophysiology
- B-cells in both primary and secondary lymphoid tissues become progressively depleted or reduced to almost undetectable numbers, which results in a progressive depletion of circulating immunoglobulins.
- The lymphoproliferative response to mitogens and antigens is diminished.
- Production of cytokines (which play an essential role on antibody synthesis and the regulation of the immune response in general) is altered, and this causes deficient expression of cell-surface molecules and the resulting immunodeficiency increases susceptibility to infection in all body systems, particularly the respiratory system and digestive tract.
- Frequent pulmonary infections may lead to bronchiectasis and recurrent airway obstruction Lung: recurrent airway obstruction (RAO) .
Timecourse
- A progressive disease in which affected horses can appear normal for many years before clinical manifestations of disease.
- The humoral immune system is already impaired by the time clinical signs appear.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Flaminio M J, Tallmadge R L, Salles-Gomes C O & Matychak M B (2009) Common variable immunodeficiency in horses is characterized by B cell depletion in primary and secondary lymphoid tissues. J Clin Immunol 29 (1), 107-116 PubMed.
- Crisman M V & Scarratt W K (2008) Immunodeficiency disorders in horses. Vet Clin North Am Equine Pract 24 (2), 299-310 PubMed.
- Pellegrini-Masini A, Bentz A I, Johns I C et al (2005) Common variable immunodeficiency in three horses with presumptive bacterial meningitis. JAVMA 227 (1), 114-122, 87 PubMed.
- Kokron C M, Errante P R, Barros M T et al (2004) Clinical and laboratory aspects of common variable immunodeficiency. An Acad Bras Cienc 76 (4), 707-726 PubMed.