Application of Transmission Electron Microscopy for Analysis of Ultrastructural Organization of Circulating Immune Complexes in Patients with Typhoid Fever and Chronic Carriers of Salmonella typhi.

Transmission electron microscopy was used to study the ultrastructural organization of circulating immune complexes (CIC), isolated from patients with typhoid fever in the different periods of acute infectious process (febrile period, period of an early and late reconvalescence), relapse and from acute and chronic carriers of Salmonella typhi in the period of pathogen excreting. It has been shown that preparations of CIC from healthy donors consisted of amorphous mean electron density material, including a cell-like detritus. At acute and chronic infectious process there were bacterial cells in a structure of the CIC. Depending on the period of disease, bacteria had different ultrastructural organization in the CIC. In the febrile period, in the period of an early reconvalescence and in the period of formation of acute carriage of S. typhi, and also in relapse, bacteria had a typical structure, with reference to gram-negative microorganisms. In the period of formation of acute and chronic carriers of S. typhi, in a period of excretion of S. typhi, bacteria in the CIC had ultrastructural organization, relevant to the forms of bacteria with a defective cell wall. Immunocytochemistry research made with the purpose of visualization the O-antigen of S. typhi in bacteria has demonstrated positive immunolabeling on the O-antigen in the bacterial forms and forms with a defective cell wall, and on amorphous mean electron density material. The analysis of ultrastructural organization of the circulating immune complexes and immunolabeling on the O-antigen of S. typhi have allowed to conclude that S. typhi, both typical bacterial form, and the forms with a defective cell wall were the main structural component of circulating immune complexes in acute and chronic forms of infectious process.