Department

AP50

Preferred Sample Type

2 mL of serum

Specimen Transport

Arrange for sample to be separated at an interim site and subsequently transport frozen to lab, if it cannot reach lab within one hour.

Sample Processing in Laboratory

Specimen should be seperated and frozen within 1 hour of venepuncture

Sample Preparation

Arrange for sample to be separated at an interim site and subsequently transport frozen to lab, if it cannot reach lab within one hour.

Turnaround Time

up to 4 weeks

Sample Stability

To be stored at -70^oC or below.

AP 50 Alternate complement pathway

General Information

AP50 is a functional measure of alternative complement pathway activity. The Alternative complement pathway is an enzyme cascade dependent on stabilisation of C3b on microbial membranes. Low AP50 values may be caused by complement consumption or deficiency of complement components or regulatory factors. Deficiencies of membrane attack complex components would lead to absent AP50 and CH50 results, whereas Factor B, D and properdin deficiencies would show normal CH50 values in the absence of AP50 activity [2,3].

Suspected complement deficiency should be investigated in anyone with an unusual strain of neisserial meningitis or recurrent infections with encapsulated bacteria

Notes

Note Change in methodology 23/05/2024.

No change of reference range or reporting units

Reference Range

Normal >75 %

Abnormal <75 %

Source of Reference Range

PRU handbook

Specifications

EQA Scheme?: No
EQA Status: No EQA scheme currently available. Sample exchange scheme has been implemented.