Antiphospholipid Antibody Syndrome

Posted by e-Medical PPT
Most common acquired thrombophilia
A syndrome characterized by the association of:
thrombosis, obstetric complications and/or thrombocytopenia
antibodies against phospholipids or against proteins bound to phospholipids.
Combination of genetic background and environmental factors: infection, trauma, drugs

Antiphospholipid Antibodies
10% of healthy donors, 30-50% of SLE patients
LA antibodies are directed against plasma proteins bound to anionic phospholipids
aCL antibodies are directed against phospholipids bound to proteins
 Can be IgA, M, or G (subclasses 1-4)
 IgG (esp G2) associated with a greater risk of APS
Anti b2GPI antibodies are directed against a plasma protein that binds phospholipid with high affinity

Lupus Anticoagulant (LA) Antibodies
 Prolonged coagulation in phospholipid-dependent in vitro tests (aPTT, PT, dRVVT)
 Failure to correct with 50:50 mix
 Correction of coagulation time by adding phospholipid
Anticardiolipin (aCL) Antibodies
 ELISA assay in the presence of bovine B2GPI
Anti-Beta 2 Glycoprotein I Antibodies (b2GPI)
 ELISA assay using human B2GPI coated plates
 most specific

Diagnosis - Clinical Criteria
Vascular thrombosis: arterial, venous, or small vessel, in any tissue or organ, confirmed by objective validated criteria
Pregnancy morbidity:
- Unexplained fetal death at or beyond 10 weeks gestation
- Premature birth before 34 weeks gestation because of
eclampsia, severe pre-eclampsia, or placental insufficiency
- Three or more consecutive spontaneous abortions before
10 weeks gestation

Diagnosis - Laboratory criteria
Lupus anticoagulant, present on at least 2 occasions, at
least 12 weeks apart
Anticardiolipin antibodies (ACA), IgG or IgM >30 units for both, present on at least 2 occasions, at least 12 weeks
apart
Anti-beta-2-glycoprotein I antibodies (anti-B2GPI), IgG or IgM >20 units for both, present on at least 2 occasions, at least 12 wks apart

A diagnosis of APS should not be made if a period of greater
than five years separates the clinical event and positive
laboratory test.

Catastrophic APS
Preliminary criteria:
1. Involvement of three or more organs or tissues
2. Development of manifestations simultaneously or in < 1 week 3. Histopathologic evidence of small-vessel occlusion in at least one type of tissue 4. Presence of lupus anticoagulant, anticardiolipin antibodies or both Definite diagnosis: All four criteria met Probable diagnosis: 2 organs or tissues involved, and the 2nd, 3rd and 4th criteria met; or All 4 criteria met and negative test for LA or anticardiolipin antibody > 6
wks after the first positive test or death within that period; or
First, 2nd and 4th criteria met; or
First, 3rd and 4th criteria met and development of a third manifestation
in >1 wk but <1 mo despite anticoagulation


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