Immunohistochemical evaluation of the cellular immune response to Rickettsia conorii in taches noires

Abstract

[EN]Significant infiltration by inflammatory cells, mainly lymphocytes and macrophages, was observed in and around blood vessels within the taches noires of patients with Mediterranean sopotted fever (MSF). Rickettsia conorii antigens were found in the endothelium (lining of blood vessels) and within these inflammatory cells, showing the primary site of infection and immune attack.This cellular response, involving T-cells and macrophages, is vital for eliminating infected cells and controlling the bacteria, but the associated inflammation also contributes to the characteristic vascular injury (vasculitis) seen in MSF. Immunohistochemistry proved effective in detecting rickettsial antigens in skin biopsies, confirming infection during the acute phase, complementing other diagnostic methods like PCR and serology.