Objectives:

This study aims to investigate whether there is an impairment of Fas-mediated lymphocyte apopotosis mechanism in patients with autoimmune lymphoproliferative syndrome (ALPS) patients.

Patients and methods:

Twenty seven patients (15 males, 12 females; mean age 12.9±2.6 years; range 4 to 45 years) who were monitored at our Immunology Unit of Hacettepe University İhsan Doğramacı Children's Hospital with suspected diagnosis of ALPS based on clinical and laboratory signs and four patients (mean age 12±11.2 years; range 3 to 27 years) with confirmed heterozygous Fas mutation who were diagnosed with ALPS-Fas, and 30 healthy individuals were included. Peripheral mononuclear cells were isolated from freshly drawn heparinized blood using ficoll-histopaque density gradient centrifugation method. These cells were activated for 12 days with phytohemagglutinin (PHA) and interleukin-2. Subsequently, they were cultured with anti-Fas monoclonal antibody for additional 48 hours. The cells were stained with trypan blue dye and apoptotic cells were counted under light microscope.

Results:

It was found that Fas-induced lymphocyte apoptosis was defective in four ALPS-Fas patients. The patients with suspected ALPS and controls had normal Fas-induced apoptosis.

Conclusion:

Our results indicate that this functional apoptosis test is useful for identification of the patients with Fas mutations. It can also be used for selecting patients for further analyses.

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