The causative mutations for familial Mediterranean fever (FMF) are located in 
the MEFV gene, which encodes pyrin. Pyrin modulates the susceptibility to 
apoptosis via its PYD domain, but how the mutated versions of pyrin affect 
apoptotic processes are poorly understood. Spontaneous and induced rates of 
systemic neutrophil apoptosis as well as the levels of proteins involved in 
apoptosis were investigated ex vivo in patients with FMF using flow cytometry 
and RT-qPCR. The freshly collected neutrophils from the patients in FMF 
remission displayed a significantly larger number of cells spontaneously 
entering apoptosis compared to control (6.27 ± 2.14 vs. 1.69 ± 0.18%). This 
elevated ratio was retained after 24 h incubation of neutrophils in the growth 
medium (32.4 ± 7.41 vs. 7.65 ± 1.32%). Correspondingly, the mRNA level for 
caspase-3 was also significantly increased under these conditions. In response 
to the inducing agents, the neutrophils from FMF patients also displayed 
significantly elevated apoptotic rates compared to control. The elevated rates, 
however, can be largely explained by the higher basal ratio of apoptotic cells 
in the former group. Monitoring of several proteins involved in apoptosis has 
not revealed any conventional mechanisms contributing to the enhanced apoptotic 
rate of neutrophils in FMF. Although the exact molecular mechanisms of 
accelerated neutrophil apoptosis in FMF remain unknown, it may provide a 
protection against excessive inflammation and tissue damage due to a massive 
infiltration of neutrophils in the acute period of the disease.