ABERRANT INTEGRIN (CR4 ALPHA(X)BETA(2), CD11C CD18) OSCILLATIONS ON NEUTROPHILS IN A MILD FORM OF PYODERMA-GANGRENOSUM/

We have previously shown that the beta(2) integrinas CR3 and CR4 physi cally and functionally interact with urokinase receptors (uPAR) on neu trophil plasma membranes in an oscillatory fashion. Ln this study we h ave analyzed neutrophils from patient SC, a 34 y old African American female, with aberrant skin window results and recurrent perianal absce sses and pretibial lesions diagnosed as pyoderma gangrenosum. Although untreated migrating normal neutrophils exhibited 20 s sinusoidal osci llations in CR4-uPAR proximity, neutrophils from SC demonstrated a fas ter oscillation (10 s) in the form of a flyback sawtooth wave. This wa veform mimicked that observed for normal neutrophils treated with subs aturating doses of the kinase inhibitors staurosporine, genistein, and erbstatin. As beta(2) integrins are regulated by phosphorylation, we tested the hypothesis that the aberrant CR4-uPAR proximity oscillation s seen in SC's neutrophils are due to defective kinase activity that m ight be balanced by a decrease in phosphatase activity. When SC's cell s are exposed to subsaturating concentrations of the phosphatase inhib itor pervanadate, this caused the CR4-uPAR oscillations to become sinu soidal in shape with a 20 s period, as seen in normal migrating neutro phils. Although SC's neutrophils were deficient in spontaneous and N-f ormyl-methionyl-leucyl-phenylalanine-induced polarization, 0.5 mu M pe rvanadate returned cell polarization to nearly normal levels, thus par alleling the acquisition of normal receptor interactions. Inasmuch as SC's cellular phenotype is mimicked by kinase inhibitors and corrected by phosphatase inhibitors, we suggest that a mutation(s) affecting th e kinetics of intracellular signaling enzymes, but not blocking the pa thway per se, may be responsible for this clinical state.