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Table 4 Methods for assessment of plasma and membrane complement proteins and screening for anti- factor H antibodies

From: Atypical hemolytic uremic syndrome

Plasma or membrane complement
Plasma concentration
(mg/L) (- 2 to + 2 SD) or membrane expression
Technique Laboratory Interpretation
C3 660-1250 Nephelometry Basic complement screen Severe complement consumption through the alternative pathway indicated by very low plasma levels of C3 and CFB. Frequently, there is only an isolated moderate decrease of C3 level with normal CFB level
CFB 93-380 Nephelometry Specialized diagnostic  
CFH 330-680
(no international standard)
ELISA Specialized diagnostic CFH or CFI less than 60% of normal are compatible with quantitative deficiency
CFI 40-80
(no international standard)
(or radial immunodiffusion)
Specialized diagnostic  
Anti-CFH Ab Screening ELISA Specialized diagnostic The title is expressed in Arbitrary Units (AU)
MCP Mean fluorescent intensity (MFI) FACS (a) with anti- MCP phycoerythrin -conjugated antibodies Specialized diagnostic No MCP expression is detected in patients with homozygous MCP deficiency. The MFI in patients of heterozygous MCP deficiency is around 50% of the normal range
  1. (a) Usually performed on peripheral granulocytes or mononuclear cells in EDTA-blood sample.
  2. Elisa, enzyme-linked immunosorbent assay; EDTA, ethylene diamine tetra-acetic acid; FACS, fluorescence-activated cell sorter.