Polymorphonuclear integrins, membrane fluidity, and cytosolic Ca2+ contentafter activation in essential hypertension

The purpose of this research was to obtain further information about the ro le of polymorphonuclear leukocytes in essential hypertension. These cells c ould be involved in the pathogenesis of organ injury. Thirty subjects (14 m en and 16 women) with essential hypertension were enrolled. In these subjec ts we determined, at baseline and after in vitro activation with 4-phorbol 12-myristate 13-acetate and N-formyl-methionyl-leucyl-phenylalanine, the po lymorphonuclear leukocyte membrane fluidity, obtained by labeling the cells with 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene, cytosolic Ca2 + concentration, obtained by marking the cells with Fura 2-AM, and integrin pattern (CD11a, CD11b, CD11c, and CD18), by using the indirect immunofluor escence with a flow cytometer. At baseline there was no difference in membr ane fluidity between normal subjects and hypertensives, whereas hypertensiv es showed an increase in cytosolic Ca2+ content and an increase of the phen otypical expression of CD11a, CD11b, and CD18. In normal subjects and in hy pertensives, after activation, no variation was found in membrane fluidity and cytosolic Ca2+ content. In normal subjects, after activation, we observ ed a significant increase of the expression of all adhesion molecules, wher eas in hypertensives we found an increase of the expression of CD11b, CD11c , and CD18 but also a decrease of CD11a. The behavior of the polymorphonucl ear leukocyte integrin profile may have several explanations, and in partic ular, the trend of CD11a after chemotactic activation may be related to its cleavage or to an altered integrin phosphorylation/dephosphorylation balan ce hypothetically present in this clinical condition.