Inflammatory response and antigen localization following immunization with influenza virus ISCOMs

The inflammatory response, antigen retention, and antigen localization was studied in mice after immunization with influenza virus glycoproteins presented in two physically defined forms--micelles and ISCOMS (immunostimulating complexes). Two hours after intraperitoneal injection, the proportion of polymorphonuclear leukocytes (PMNs) in peritoneal lavage cells increased from less than 1% to 82% in ISCOM-treated mice and from less than 1% to 41% of the total cell count in micelle-treated mice. For both treatment groups, the proportion of PMNs returned to around zero 24 h postimmunization. Total recovery of radioactive antigen was significantly greater (P less than 0.05) in ISCOM-treated than in micelle-treated mice at one, two, and eight days postinjection. At all times tested, animals given ISCOMs had significantly more radioactive antigen in their spleens than animals given micelles. By electron microscopy ISCOMs were found to attach externally to the plasma membrane or within phagosomes of macrophages in close association with the membranes.