RESUMO
The influence of Y. pestis phospholipase D on the physiological state of leukocytes in the blood of guinea pigs was studied in vivo by flow impulse fluorometry with the use of fluorochrome acridine orange. During the first hours of observation the intensity of leukocyte fluorescence increased due to a rise in the number of polymorphonuclear leukocytes and changes in the permeability of cell membranes. Further changes in the intensity of the fluorescence of the material under study after 24 hours of observation occurred due to the appearance of activated lymphocytes in the blood stream. The processes normalized by day 21. The reaction of blood leukocytes to phospholipase D was specific in comparison with the reaction to capsular antigen, "mouse" toxin, lipopolysaccharide and the main somatic antigen.