Hunter Area Pathology Service

Research

• Communique List
• Research
• Information Sheets

Anti-Phospholipid Antibodies

(January 2005)

(Download  AntiPhospholopid Antibodies.pdf)

Background

Anti-phospholipid antibodies (APLA) are misnamed, as they are directed against protein-phospholipid complexes or proteins alone. The APLA antibodies are believed to have functional effects upon the coagulation cascade, resulting in a thrombophilic state, possibly through interference with natural anticoagulant factors.

Clinical Presentation

The anti-phospholipid antibody syndrome presents as:

• Clotting events (arterial, venous)
• Livedo reticularis (net-like rash on extremities)
• Obstetric complications (miscarriages, pre-eclampsia IUGR, prematurity)
• Thrombocytopaenia (and sometimes other cytopaenias)

Diagnosing APLA

There are two major subsets of APLA:

Lupus anticoagulants (LA):

• Immunoglobulins interfering with one or more in vitro phospholipid-dependent coagulation tests [eg APTT, KCT (Kaolin clotting time), RVVT (Russell viper venom time)] resulting in prolongation of the clotting time, hence the misnomer "anticoagulant".
• Antigenic targets include: prothrombin, and sometimes ¸ 2-glycoprotein-I (¸ 2GPI).
• Tests for LA are affected by anticoagulant therapy.

Anti-cardiolipin antibodies (ACLA):

• Immunoglobulins directed against phospholipids (including phosphatidylserine).
• Antigenic targets include: b 2GPI (++), rarely others.
• ELISA Immunoassay technology not affected by anticoagulants.

Diagnostic Interpretation

• IgG ACLA is associated with thrombophilia.
• LA are possibly more predictive of clotting events than IgG ACLA.
• LA and ACLA are discordant in up to 40% of cases, so when the phospholipid antibody syndrome is clinically suspected, both tests should be requested.
• Rare individuals with phospholipid syndrome are negative for IgG cardiolipin antibodies and lupus anticoagulant. In these settings, discussion with a specialist haematologist or immunologist should occur to discuss whether further testing with IgM cardiolipin and/or ¸ 2-glycoprotein antibodies is indicated.

About the Authors

This HAPS Communique was written by Drs Glenn Reeves, Immunology Staff Specialist and Michael Seldon, Haematology Staff Specialist.

If you have any questions regarding this topic Drs Reeves and Seldon can be contacted on Telephone: (02) 49214000, Facsimile: (02) 49214400.

Haematology Clinical Contacts

Dr Arno Enno - 49211220
Dr Michael Seldon (Director) - 49211220
Dr Sandra Deveridge - 49211212
Dr Phillip Rowlings - 49211212
Haematology Laboratory - 49214407

Immunology Clinical Contacts

Professor Robert Clancy - 49236135
Dr Glenn Reeves - 49214000
Immunology Laboratory - 49214018