OBJECTIVE: To investigate apoptosis, proliferation and Fas ligand expression of 
placental trophoblast in the hemolysis, elevated liver enzymes, low platelets 
(HELLP) syndrome and in pre-eclampsia (PE), and to compare this with normal 
pregnancies.
DESIGN: Prospective study.
SETTING: University hospital in Croatia.
SAMPLE: Placentae from women with HELLP syndrome (n=10), PE (n=10) and normal 
pregnancies (n=10).
METHODS: The HELLP syndrome was diagnosed with platelets <100×10(9) /L, 
aspartate aminotransferase (AST) and alanine transaminase (ALT) >70 U/L and 
lactic acid dehydrogenase (LDH) > 600 U/L. Pre-eclampsia was diagnosed at blood 
pressure >140/90 mmHg, with proteinuria >300 mg/L/24 hours. For detection of 
apoptosis and proliferation in villous trophoblast, antibodies M30 and Ki-67 
were used. Expression of Fas ligand was assessed using immunohistochemistry and 
the semiquantitative HSCORE method.
MAIN OUTCOME MEASURES: Apoptosis, proliferation and Fas ligand expression in 
villous trophoblast.
RESULTS: Apoptosis, proliferation and Fas ligand expression were higher in 
villous trophoblast in HELLP syndrome than in the PE group (p=0.015, p=0.018 and 
p=0.002, respectively) and the control group (p=0.000, p=0.012 and p=0.049, 
respectively). Placentae from the PE group had higher levels of apoptosis 
(p=0.019), lower Fas ligand expression (p=0.029) and no difference in 
proliferation (p=0.887) compared with the control group.
CONCLUSIONS: There is an increase in apoptosis, proliferation and Fas ligand 
expression in placentae from women with HELLP syndrome compared with placentae 
from PE and normal pregnancies. Our findings indicate the possibility of 
differential mechanisms behind HELLP syndrome and PE.