Factor B

Immunology

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Description

Factor B, Factor D and properdin are essential in the stable initialisation of the alternative complement pathway. Factor B is present in the blood as a single chain polypeptide that is cleaved by Factor D when the alternative pathway is activated. Cleavage results in two subunits being formed: Bb and Ba. Bb associates with C3b to form the alternative pathway C3 convertase [1]. Deficiency in Factor B is rare and may lead to recurrent infections with encapsulated bacteria.

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Indications

Investigation of complement alternative pathway deficiency. Indicated if AP50 activity is reduced by CH50 activity is normal.

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Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Normal range: 295 - 400 mg/L.

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Turnaround Time

Within 14 days

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Testing Frequency

As required (send away test).

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References

Slade C, Bosco J, Unglik G, et al. Deficiency in complement Factor B. N Engl J Med. 2013, 369: 1667-1669. [Ref 1].

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