Role of Placenta Growth Factor in Sickle Acute Chest Syndrome

The proposed research is a clinical study designed to test the hypothesis that PlGF levels in blood at baseline in patients with SCD will correlate with leukotriene (LT) levels and will be reflective of the degree of airway obstruction; and that acute elevations in PlGF levels will occur during an acute sickle event and precede clinical and radiological recognition of ACS. This is a biological study that does not fall into the criteria of a phase I-IV trial. Measurements will be done at two stages. First, patients who are admitted to the hospital with an acute sickle event will have a daily evaluation for the first 4 days of the admission or up until the patient has an ACS event. Measurements of inpatient spirometry (at primary site only) and impulse oscillometry will be performed daily. Measurements on 35 ACS events with ACS developing on the 3rd/4th day of admission will be collected. Measurements on patients developing ACS will be compared to those who do not develop ACS will allow for earlier prediction of ACS. Finally, patients who have an ACS or admission for an acute sickling event will be evaluated again after 3-4 weeks in order to get a baseline measurement. One hundred baseline measurements will be made. Twenty of these baseline patients will also have one or two additional baseline evaluations at subsequent clinic visits to evaluate the overall non-event baseline distribution and intra-subject baseline variability. Patients will have measurements repeated if admitted for an acute event greater than one year since the last baseline measurement . These measurements will be used to see if there is any prognostic information for a subsequent acute or ACS event. Some patients may only have baseline data collected.