Pediatric Pulmonary and Sleep Medicine Research

Laboratory Research

In collaboration with adult Pulmonary Allergy and Critical Care Medicine and our CF Affiliate Center headed by Dr. Joanne Billings, we perform testing and contribute data and specimens to projects funded by the Cystic Fibrosis Therapeutics Development Network, a nationwide effort of CF centers to evaluate new therapies for CF.

Clinical Testing

We offer clinical testing of neutrophil function in our CLIA certified Host Defense Laboratory. Three tests are available for screening patients suspected of having a neutrophil-based immune deficiency. Call 612-624-0438 to schedule testing.

Neutrophils are first separated from the peripheral venous blood sample by a standard process, then tested in any or all of the following procedures:

Chemiluminescence is a quantification of the relative amount and rate of reactive oxygen products generated by neutrophils after stimulation by serum opsonized zymosan particles and by phorbol-myristate-acetate. The chemiluminescence assay measures the light produced when the reactive oxygen compounds react with luminol. Normal quantities of light are produced 1) if the cells can take up particles at a normal rate and 2) if the cells can be stimulated to generate the light-producing biochemical reaction that is associated with normal intracellular killing of bacteria and fungi. This test is useful for patients with recurring infections and in diagnosis of chronic granulomatous disease.

Nitroblue tetrazolium reduction is also a measure of reactive oxygen products. This method allows microscopic examination and percent quantitation of neutrophils that generate superoxide in response to phorbol-myristate-acetate and therefore reduce the NBT dye, forming insoluble intracellular granules (formazan). This test is useful in the diagnosis of chronic granulomatous disease.

Chemotaxis under agarose measures the distance neutrophils migrate under a layer of agarose toward a chemical gradient of zymosan activated serum (C5a) and to the peptide N-formyl-methionyl-leucyl-phenylalanine. Adhesion to the tissue culture substrate is the initial step required for cells to chemotax and subsequently, the ability to move randomly as well as orient in the chemical gradient. Approximately twenty clinical syndromes with abnormal chemotaxis have been described in the literature. This test is an aid to diagnosis of neutrophil adhesion molecule defects in patients with recurrent infections.