PHOSPHOLIPASE A(2) LEVELS IN ACUTE CHEST SYNDROME OF SICKLE-CELL DISEASE

Acute chest syndrome (ACS) is associated with significant morbidity an d is the leading cause of death in patients with sickle cell disease ( SCD). Recent reports suggest that bone marrow fat embolism can be dete cted in many cases of severe ACS. Secretory phospholipase A(2) (sPLA(2 )) is an important inflammatory mediator and liberates free fatty acid s, which are felt to be responsible for the acute lung injury of the f at embolism syndrome. We measured sPLA(2) levels in 35 SCD patients du ring 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, a nd during 12 clinic visits when patients were at the steady state. Ele ven non-SCD patients with pneumonia were also evaluated. To determine a there was a relationship between sPLA, and the severity of ACS we co rrelated sPLA, levels with the clinical course of the patient. In comp arison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non-SCD pa tients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD p atient groups had an elevation of sPLA(2) (steady state mean = 10.0 +/ - 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mea n = 336 +/- 209 ng/mL). In patients with ACS sPLA(2) levels were 100-f old greater than normal control values, 35 times greater than values i n SCD patients at baseline, and five times greater than non-SCD patien ts with pneumonia. The degree of sPLA(2) elevation in ACS correlated w ith three different measures of clinical severity and, in patients fol lowed sequentially, the rise in sPLA(2) coincided with the onset of AC S. The dramatic elevation of sPLA(2) in patients with ACS but not in p atients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of sPLA, and clinical severity sugg est a role for sPLA(2) in the diagnosis and, perhaps, in the pathophys iology of patients with ACS. (C) 1996 by The American Society of Hemat ology.