Role of CD45 signaling pathway in galactoxylomannan-induced T cell damage.
Previously, we reported that Galactoxylomannan (GalXM) activates the extrinsic and intrinsic apoptotic pathways through an interaction with the glycoreceptors on T cells. In this study we establish the role of the glycoreceptor CD45 in GalXM-induced T cell apoptosis, using CD45(+/+) and CD45(-/-) cell lines, derived from BW5147 murine T cell lymphoma. Our results show that whereas CD45 expression is not required for GalXM association by the cells, it is essential for apoptosis induction. In CD45(+/+) cells, CD45 triggering by GalXM reduces the activation of Lck, ZAP70 and Erk1/2. Conversely, in CD45(-/-) cells, Lck was hyperphosphorylated and did not show any modulation after GalXM stimulation. On the whole, our findings provide evidence that the negative regulation of Lck activation occurs via CD45 engagement. This appears to be related to the capacity of GalXM to antagonize T cell activation and induce T cell death. Overall this mechanism may be responsible for the immune paralysis that follows GalXM administration and could explain the powerful immunosuppression that accompanies cryptococcosis.
Pericolini
Eva
E
Microbiology Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy.
Gabrielli
Elena
E
Bistoni
Giovanni
G
Cenci
Elio
E
Perito
Stefano
S
Chow
Siu-Kei
SK
Riuzzi
Francesca
F
Donato
Rosario
R
Casadevall
Arturo
A
Vecchiarelli
Anna
A
D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003455:Cryptococcus neoformans / Q000378:metabolism; D015870:Gene Expression; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008213:Lymphocyte Activation; D051379:Mice; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*
D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; C043689:galactoxylomannan; D017493:Leukocyte Common Antigens