Immunodeficiency, Selective Immunoglobulin M

Immunodeficiency, Selective Immunoglobulin M



Basic Information image



Definition


An immunodeficiency syndrome characterized by low or absent serum immunoglobulin M (IgM) with normal or elevated levels of other immunoglobulin classes



Epidemiology



Species, Age, Sex




• Probably of genetic origin and hence a primary immunodeficiency, but breeding studies have yielded inconclusive results


• Most often reported in Arabians and Quarter Horses but other breeds also affected



Clinical Presentation



Disease Forms/Subtypes




• Recurrent severe infections, especially diarrhea, arthritis, or respiratory disease leading to death before age 10 months


• Foals with a history of repeated infections that usually respond to aggressive antibiotic treatment. Infections recur after treatment has stopped. These foals do poorly and show stunted growth but may survive for several years.



Etiology and Pathophysiology




• Foals have unusually low levels of IgM. This may be because of decreased production or increased catabolism or because of excessive regulatory T-cell activity.


• Lymphocyte counts are usually within normal ranges, so there is no gross B- or T-cell deficit.



Diagnosis image



Differential Diagnosis




• Other primary immunodeficiencies


• Failure of passive transfer


• Delayed immunoglobulin synthesis


• Infections not associated with immunodeficiency, upper respiratory tract infections, chronic diarrhea, sepsis, arthritis, bacteremia



Initial Database




• Complete blood count (CBC) and serum chemistry profile may reflect the ongoing infection and inflammation


• Bacterial culture and sensitivity



Advanced or Confirmatory Testing




• Serum protein electrophoresis to evaluate immunoglobulin concentrations.


• Serum immunoglobulin quantitation.


• Serum IgM levels are more than two standard deviations below the age-specific normal IgM levels.


• Multiple IgM assays must be performed to confirm that the levels are persistently depressed.


• Other immunoglobulin classes are within normal limits or elevated for age.


• On necropsy lymphoid tissues are apparently normal. Evidence of bacterial infection, pneumonia, sepsis, and arthritis is present.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Immunodeficiency, Selective Immunoglobulin M

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