Elliptical galaxies exhibit a very large dispersion of X-ray luminosities for given optical luminosity. X-ray bright galaxies posses a fairly dense ISM, and materials being lost by stars can either be in a global outflow or inflow subsonic motion. X-ray faint galaxies are instead likely to host a supersonic wind that effectively evacuates the galaxies of stellar mass loss materials. In the various cases very different thermal histories are expected for the grains forming in the circumstellar shells of mass losing stars. Our idea is to observe with ISO a representative sample of elliptical galaxies exhibiting extreme X-ray to optical luminosity ratios.