Young and Old Animals Use Different Strategies for Forming an Immune Response to Infectious Agents (Pseudomonas aeruginosa and Escherichia coli)

Abstract

This paper presents the results of a study of the features of the immune response to the injection of bacterial suspension (Pseudomonas aeruginosa and Escherichia coli) in young (3 months) and old (20 months) Wistar rats at 3, 5, and 7 days after infection. We assessed the contents of circulating immune complexes (CICs) and complement components C3 in dynamics and the activity of oxygen-dependent and oxygen-independent phagocytosis. Bacterial infection was accompanied by a multiple increase in the content of circulating immune complexes in young and, especially, in old animals. It remained at a high level from the third to the seventh day of the pathology development in young animals, while their content decreased to the seventh day in old animals. In the presence of infectious process, the content of complement components C3 decreased in young animals, and it increased in old animals, in the case of infection with P. aeruginosa and E. coli. The activity of oxygen-dependent and oxygen-independent phagocytosis decreased in different ways in young and old infected animals, i.e., the ratio of the forms of phagocytosis in old and young animals was different. Old animals were not inferior to the young ones in terms of the ability of the immune system to respond to the presence of an infectious agent. They used a different strategy for eliciting the immune response.