HUMAN NEUTROPHILS ARE DEVOID OF THE INTEGRAL MEMBRANE-PROTEIN CAVEOLIN

The secretory vesicles of human neutrophils are rapidly mobilizable ve sicles that contain several GPI-Linked proteins, a characteristic feat ure of caveolae in other cells. To investigate whether secretory vesic les are structurally related to caveolae, we examined human neutrophil s for the presence of caveolin, a major constituent of caveolae, by im munoblotting using monoclonal and polyclonal antibodies. Caveolin was not detected in lysates of human neutrophils nor in isolated plasma me mbrane/light membrane fractions in which secretory vesicles localize. In contrast, caveolin was readily detected in isolated membranes of ad ipose cells. We conclude that human neutrophils are devoid of caveolin and that secretory vesicles are not related to caveolae nor dependent on caveolae for mobilization.