Author/Editor		Hof, Herbert
Title		Defense machanisms in listeriosis: a model for cell-mediated immunity
Translated title		Obrambni mehanizmi pri listeriozi: model celično posredovane imunosti
Type		članek
Source		Med Razgl
Vol. and No.		Letnik 39, št. Suppl 4
Publication year		2000
Volume		str. 25-34
Language		eng
Abstract		Among the various species of the genus Listeria only L. monocytogenes is regarded as facultative pathogenic; there is a broad spectrum of animals which are susceptible to these bacteria thus the mouse serves as a model for studying the pathophysiology of this infection. The multiplication in the mouse takes place primarily in the spleen and liver. Thereby, the bacteria multiply within host cells. Listeriae are unique in their behaviour to leave the phagocytic vacuole and to penetrate into the cytosol of the host cell. In principle they are able to spread from cell to cell so that there is no extracellular stage necessary. This means that humoral defense mechanisms are of minor importance. At the beginning of infection non-specific defense is mediated by polymorphonuclear granulocytes. This may help to slow down the multiplication rate, but curing is only achieved when a T cell-mediated immune response takes place, Nude, athymic mice devoid of T-lymphocyces are unable to mount any imunity. Certain bacterial epitopes which are processed intracellulary in the host cell are presented at the surface of the host cell in the context of MHC class I or class II molecules. The antigenic epitopes presented by MHC class I are recognized by CD8+T cells, whereas epitopes on MHC class II are presented to CD4+T cells. Both types of T-lymphocytes are involved in protection against L. monocytogenes. By this strong immune reaction the bacterial infection is abrogated after a few days; this immunity will persist for months but gradually declines with time.
Summary		Med mnogimi vrstami, ki sodijo v rod Listeria, so samo predstavnice iz vrste L. monocytogenes fakultativno patogene. Listerije lahko povzročijo bolezen pri mnogih živalskih vrstah, za raziskovanje njihovih fizioloških lastnosti pa so najprimernejše miši. Po okužbi se mikrobi prvenstveno razmnožujejo v vranici in jetrih. Razmnoževanje je znotrajcelično. Po fagocitozi mikrobi zapustijo fagocitni mehurček in prodrejo v citosol. Iz okužene celice lahko preidejo v sosednje celice, ne da bi prišle v medceličnino. Tako se in vivo uspešno izognejo delovanju protiteles. Ob začetku okužbe so za obrambo pomembni polimorfonuklearni levkociti, ki upočasnijo povečevanje števila listerij, do ozdravljenja pa pride le, če se razvije celični imunski odziv Dokaz za to je, da je okužba pri golih miših, ki so brez limocitov T, navadno smrtna. Antigeni, ki nastajajo med znotrajceličnim razmnoževanjem, se izpostavijo na celični površini skupaj z molekulami MHC razredov 1 in 2. Epitope, ki jih predstavljajo molekule MHC1, prepoznavajo limfociti CDB+, epitope, ki jih predstavljajo molekule MIHCII, pa limfociti CD4+. Pri zaščiti pred L. monocytogenes so pomembni oboji. Okužba izzveni v nekaj dneh, imunski odziv pa se ohrani še več mesecev, vendar se njegova moč s časom zmanjšuje.
Descriptors		LISTERIA INFECTIONS MACROPHAGES IMMUNITY, CELLULAR VACCINATION LISTERIA MONOCYTOGENES