[Flow-cytofluorometric study of bactericidal granules in blood phagocytes of animals with various species sensitivity to experimental plague infection].

The researchers conducted a study to compare the content of bactericidal granules (BG) in blood phagocytes of various animal species, with different sensitivity levels to plague infection. It was found that blood phagocytes lacking adequate levels of BG, especially leukocyte elastase, were more prone to plague infections.

Methods

• The researchers studied the leukocytes (white blood cells) in human whole blood along with blood from seven different animal species – mice, guinea pigs, golden hamsters, white rats, rabbits, dogs, and horses.
• To mark the bactericidal granules in phagocytes (a type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles), a dye known as Acridine Orange (AO) was used.
• The content of BG in individual cells was measured in conventional units of red fluorescence intensity through a method known as flow cytofluorometry. This technique allows for the automatic differentiation of monocytes (a type of white blood cell) and granulocytes (a category of white blood cells characterized by the presence of granules in their cytoplasm) of human blood.

Results

• The study established a correlation between the deficiency of AO molecules in BG and the deficiency of leukocyte elastase within cells. This was most noticeable in mice and least noticeable in rabbits.
• This deficiency was found to be characteristic of all blood phagocytes in all the laboratory-animal species examined that were sensitive to plague.
• Animal species that were not sensitive to plague, particularly dogs and horses, exhibited high heterogeneity by the measure used for BG. The blood phagocytes of horses were found to contain 2.5 times the amount of BG compared to human granulocytes.

Conclusions

• The research concluded that leukocyte bactericidal granules, which contain enzyme cationic proteins like elastase, cathepsin G, protease 3, and myeloperoxidase, play a crucial role in protecting the organism from plague infection.
• The presence or absence of these BG, and differences in their amounts, could help determine the sensitivity or resistance of an organism to plague infection.