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Alternative Pathway Complement Function (AP50)


Alternative Pathway Complement Function (AP50)
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Reference Range:

66 - 129 %

Turnaround Time:

28 Working Days


Internal Test Code - CACF


Indication:- Recurrent bacterial infections.

Background:- Tests functional activity of alternative and lytic components of complement system. Reduced activity if any of alternative or lytic complement components are low/absent. Defects in alternative pathway are very rare.

Method:- Radial Immunodiffusion (RID)

Repeat Frequency:- Only to confirm abnormal result.


Contact laboratory if advice regarding sample requirements needed.

Vessels and Containers:

Serum gold-top

Sample Requirements:

250µl serum - See transportation and handling


Microbially contaminated, haemolysed, very lipaemic or samples containing particulate matter should not be used. Sera from patients with rheumatoid arthritis may show poor or multiple rings of lysis.

How result is reported:

Percentage of normal activity
Performed alongside classical pathway complement function (CH100) assay

Important Information:

Entry Last Modified 22/05/2019


Complement Function, AP100, AP50

Transportation and Handling:

Sample must reach Immunology lab within 2 hours of venesection. If this is not possible, please arrange for sample to be separated into two small aliquots and frozen at -20°C. Separated serum should then be sent on dry ice to Immunology.

Special Precautions:


Time limits for requesting additional examinations:

This test cannot be added to existing requests. Please send a new request and sample.