CONTRIBUTION OF PHAGOCYTIC-CELLS AND BACTERIA TO THE ACCUMULATION OF TC-99M LABELED POLYCLONAL HUMAN-IMMUNOGLOBULIN AT SITES OF INFLAMMATION

The purpose of this study was to assess the contribution of phagocytic cells and bacteria to the accumulation of technetium-99m labelled pol yclonal human immunoglobulin (HIG) at sites of inflammation. Mice were intraperitoneally injected with Straphylococcus aureus (SA animals), with heat-inactivated newborn calf serum (NBCS, to mimic a non-bacteri al inflammation) or with physiological saline (controls); 1 h thereaft er they received HIG, At various intervals after the administration of HIG the mice were killed, and the percentages of radioactivity in the peritoneal effluent and attached to the cellular and bacterial fracti on thereof were established. Furthermore, the total number of cells an d that of bacteria in the fluid were quantitated, The percentage of ac tivity in the effluent in the SA animals was (P<0.02) higher than thos e in the NBCS-injected animals and controls from 4 h onwards. In all g roups of mice this percentage was highest at 4 h and decreased (P<0.01 ) afterwards. The percentage of cell-bound activity and the total numb er of cells remained fairly constant or increased with time in the SA animals (P<0.01). The bacteria-bound activity remained rather constant throughout the experiment and ranged between 4% and 6%. In the SA-inf ected animals the percentage of cell-bound activity was correlated wit h the total number of cells (macrophages but especially neutrophils) b ut even more strongly with the number of cell-associated bacteria. In the NBCS-injected animals a correlation was demonstrated between the c ell-bound activity and the total number of cells (only neutrophils). I t is concluded that in both experimental inflammations, phagocytic cel ls, and especially neutrophils, contributed significantly to the accum ulation of label at the site of inflammation. Their impact on this loc alization is augmented by the phagocytosis of bacteria.