Pathophysiological effects of infection with Gram-negative bacteria depend on recognition by host cells of LPS, a major component of the outer membrane of these microorganisms. CD14 is an immunological marker and also the receptor for LPS on phagocytic cells. The aim of the present study was to investigate the capacity of a bacterial immunomodulator, named Cantastim, which is used as a therapeutical agent in neoplasic diseases and chronic infections, to modulate the CD14 expression on human granulocytes. Our preliminary results showed that Cantastim can not influence the expression of CD14 on granulocytes obtained from healthy donors, but on the other hand Cantastim was able in vitro and in vivo to down-regulate the expression of this marker on granulocytes from a patient with neoplasic disease.