Table I.

Diagnostic criteria.

(a) Original diagnostic criteria (Bleesing et al, 2000)

1. Chronic non-malignant lymphoproliferation

2. Elevated peripheral blood DNTs

3. Defective in vitro Fas-mediated apoptosis

Supporting: genetic mutations; autoimmunity

Diagnosis: Must meet all three criteria

(b) New Diagnostic Criteria (Seif et al, 2008)

Major criteria

1. Chronic non-malignant lymphoproliferation

(a) >6 months

(b) Splenomegaly and/or lymphadenopathy of ≥2 nodal groups

2. Marked elevation in peripheral blood DNTs ≥5%*

3. Defective in vitro Fas-mediated apoptosis

4. Identifiable genetic mutation (FAS, FASLG, CASP10, NRAS): germline or somatic

Minor criteria

1. Autoimmune cytopenias

(a) Thrombocytopenia, neutropenia and/or haemolytic anaemia, and

(b) Proven to be immune-mediated by identifiable autoantibody (e.g. DAT) or response to      immunosuppressive medication

2. Moderate elevation in DNTs*

(a) Elevated DNTs in spleen or lymph node biopsy, and/or

(b) Peripheral blood DNTs >2 S.D. of testing labs mean and <5%

3. Elevated serum IgG

4. Elevated serum IL-10

5. Elevated serum vitamin B12

6. Elevated plasma Fas ligand level

Diagnosis: three major criteria or two major plus two minor criteria

DNT, double negative T cells; DAT, direct antiglobulin test.

^*One criterion must be elevated DNTs.