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A comparative study on the phagocytic capacity of human and rat polymorphonuclear leucocytes was performed. The activity of rat leucocytes was assessed by using the rat polyvinyl sponge model and the granuloma pouch model. Isolated human leucocytes were either suspended in buffer or homologous serum. Assessments of the susceptibility of Pseudomonas aeruginosa or Klebsiella pneumoniae to the antimicrobial action of leucocytes revealed that the activity of normal human leucocytes and rat leucocytes was very similar, whereas human leucocytes obtained from chronically infected patients were significantly more active. Pretreatment of the bacteria with subinhibitory mezlocillin and azlocillin concentrations with or without immunoglobulin G rendered the bacteria more susceptible to the antimicrobial action of both types of leucocytes. Again results obtained by the different methods were very similar.

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.

Phagocytic capacity and the amount of PMN-granulocytes which take part in phagocytosis was investigated in patients with septicemia and polytrauma patients in comparison to PMN-granulocytes withdrawn from healthy volunteers by use of a standardized test-system in which autoclavated S.cerevisiae is the phagocytic agent. Influence of polyvalent immunoglobulin preparations together with patients' own serum incubation was compared with serum preincubation only in the test system mentioned above. It became evident that phagocytic capacity and the number of PMN-granulocytes which take part in phagocytosis in patients with septicemia are primary on a significant higher rate than those of other groups. PMN-granulocytes from polytraumated patients showed a significant higher rate on ingestion of S.cerevisiae pretreated with patients' own serum - especially after preopsonisation with immunoglobulins - than granulocytes from patients with septicemia or healthy volunteers.

Ten strains of Pseudomonas aeruginosa isolated from different clinical sources were incubated with immunoglobulin preparations for i.v. use. This resulted in the release of beta-lactamases normally cell-bound in the periplasmic space. The amount of released beta-lactamases - depending on the degree of cell wall alteration - was spectrophotometrically determined by the use of nitrocefin as an indicator substance. beta-lactamase release varies according to strain specificity and depends on the chemical modification of the immunoglobulins used.