(Facultad de Veterinaria y Zootecnia-UNAM, 2001-04) Arestegui, Mirta B.; Gualtieri S., Catalina; Domínguez, Javier; Scharovsky, O. Graciela
Non-specific resistance is a fundamental component of the host immune response. The mononuclear phagocytic
system (MPS) is part of innate resistance effector mechanisms, and is involved in several homeostatic, inflammatory
and immunologic events. Mononuclear phagocytes (MNP), which are cells belonging to the MPS, play a central role
in the main functions of multicellular organisms. Its early interaction with pathogens determines the evolution of the
infection. Bacteria, which can resist intracellular death, survive and multiply within the cells of the MPS, are
considered endocellular parasites. Brucella genus that infects humans as well as several animal species is an
endocellular pathogen. The vast majority of these microorganisms includes mechanisms genetically coded that enable
them to invade and to survive within the host cells. In the present review, characteristics of Brucella genus are
described; special reference is dedicated to its antigenic composition, virulence factors, as well as its genomic structure
and the control of gene expression. Interaction between MPS and Brucella spp, and the effector mechanisms of MNP,
mainly, plus the generation of oxygen and nitrogen radicals, the limitation in iron availability and cytokine production
are analyzed. The control of infection is explained by cell mediated immunity and the phenomena of natural resistance
is also taken into consideration.