CD8 is critically involved in lymphocyte activation by a T. brucei brucei-released molecule.
T. brucei brucei released a lymphocyte triggering factor (TLTF), which triggered purified CD8+, but not CD4+, T cells to interferon gamma (IFN-gamma) mRNA expression and secretion and to [3H]thymidine incorporation. TLTF also induced mRNA for transforming growth factor beta, but not for interleukin-4. The action of this TLTF on mononuclear cell (MNC) cultures was blocked by anti-CD8 antibodies and by soluble CD8. MNCs from a mutant mouse strain lacking CD8 expression were not triggered by TLTF. IFN-gamma provides a growth stimulus for T. brucei brucei, and infected CD8- mice had much lower parasitemia and survived longer than CD8+ mice. The host-parasite interaction in experimental African trypanosomiasis thus involves parasite release of TLTF, which by binding to CD8 triggers CD8+ cells to produce the parasite growth-promoting cytokine IFN-gamma.
Olsson
T
T
Department of Neurology, Karolinska Institute, Huddinge Hospital, Sweden.
Bakhiet
M
M
Höjeberg
B
B
Ljungdahl
A
A
Edlund
C
C
Andersson
G
G
Ekre
H P
HP
Fung-Leung
W P
WP
Mak
T
T
Wigzell
H
H
Fiszer
U
U
Kristensson
K
K
D000818:Animals; D016827:CD8 Antigens / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D002478:Cells, Cultured; D006790:Host-Parasite Interactions; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008213:Lymphocyte Activation; D051379:Mice; D008817:Mice, Mutant Strains; D012333:RNA, Messenger; D051381:Rats; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000469:parasitology; D013936:Thymidine / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000502:physiology*
D016827:CD8 Antigens; D007375:Interleukin-1; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma; D013936:Thymidine