In vitro molecular reconstitution of the respiratory burst in B lymphoblasts from p47-phox-deficient chronic granulomatous disease

Abstract

Epstein-Barr virus-transformed lymphocytes generate superoxide in response to various agonists in an enzymatic reaction similar to that which occurs in stimulated phagocytes. We generated transformed B lymphoblast cell lines from controls, from four patients with p47-phox-deficient chronic granulomatous disease, and from three parents. The cells from controls and from the parents generated 7.0-35 nmol of O2- /107 cells per 30 min in response to phorbol myristate acetate. None of the patient cell lines generated any detectable Superoxide. Both p47-phox and p67-phox were detected by immunoblot in the cytosol of control and parent cell lines and, as in neutrophils, these proteins had affinity for GTP-agarose. The patients' cell lines contained no detectable p47-phox by immunoblot. mRNA for both cytosolic proteins was detected in all cell lines. We generated cDNA and obtained multiple clones from two patients by poly merase chain reaction. One patient was a compound heterozygote with each allele resulting in an early stop codon. Clones derived from the other patient demonstrated only a GT deletion at base 75. The cDNA for p47-phox was inserted into an EBV-expression vector and stably transfected cell lines were obtained using hygromycin B selection. Transfected cell lines from a p47-phox-deficient patient generated normal levels of Superoxide and had readily detectable cytosolic p47-phox. Thus, B lymphoblasts provide an excellent model system for studies of the NADPH oxidase, for expression of functional recombinant forms of oxidase components, and for initial experimental approaches to genetic reconstitution in CGD.