Search

After determination of granulocyte basic parameters of polymorphonuclear neutrophilic leukocytes obtained from 5 unselected intensive care unit patients and 5 healthy volunteers phagocytosis of an E. coli strain isolated from clinically proven infection (urinary tract infection) was investigated with and without preincubation of the strain with subinhibitory concentrations (1/4 and 1/2 minimum inhibitory concentration; incubation time: 30 min) of cefaclor, erythromycin and doxycycline. The results show that it is very difficult to compare granulocyte functions because they differ widely in individual ranges among both groups. Nevertheless in comparison to the untreated strain a higher amount of ingestion by the granulocytes of both collectives could be obtained after preincubation with cefaclor or erythromycin; thereby cefaclor seemed to be the most effective drug.

The effect of azlocillin, ticarcillin and cefsulodin, respectively, on the susceptibility of Pseudomonas aeruginosa to the antimicrobial action of human polymorphonuclear leukocytes (PMN) was investigated under two different experimental conditions. Firstly, phagocytic capacity as well as bactericidal activity of PMN were assessed in a homologous system, i.e. the clinical isolate as well as the PMN and serum were obtained from the same patient. Secondly, ultrastructural studies were performed by electron microscopy. Preincubation of bacteria with subinhibitory beta-lactam concentrations augmented the phagocytic capacity as well as the antibacterial activity of PMN; azlocillin tended to be the most effective drug in this respect. The enhanced susceptibility to leukocyte killing is not due to an increased antibacterial action of the beta-lactams in the presence of PMN. These findings suggest that a non-immunological linkage between bacteria and PMN may exist which may be based on the interaction between bacterial- and eukaryotic surface structures, respectively. It may be assumed that the antipseudomonal beta-lactam antibiotics may cause changes in the surface structures of P. aeruginosa, thus rendering them more susceptible to phagocytosis. Preliminary data indicate that the lectins on the outer membrane of P. aeruginosa are not mannose sensitive. Electron microscopic studies revealed that azlocillin pretreatment of bacteria brought about a high undulation and a disruption of the outer membrane. These morphological changes may render bacteria more vulnerable to the antimicrobial action of PMN. It may be speculated that an interference with surface adhesins and induction of morphological changes may affect engulfment and intracellular killing of bacteria.

Heat inactivated S. cerevisiae as phagocytic particle and subsequent staining with trypan blue-eosin solution is suitable to give evidence of phagocytic capacity and the number of human polymorphonuclear leucocytes which are engaged in phagocytosis. After preincubation of the yeasts with i.v. IgG-preparations--and on a higher rate--with volunteers' own serum increase of phagocytic capacity and of the number of granulocytes which take part in phagocytosis occurs. The test is suitable to compare this granulocyte function of patients under different clinical conditions depending on the underlying disease and seems to be of use to decide where clinical application of polyvalent immunoglobulin therapy is indicated.