STUDY OF SPLENIC MYELOID-DERIVED SUPPRESSOR CELLS IN CPG-ODN+IFA-TREATED TUMOR BEARING MICE

FLORENCIA HARMAN; SOFÍA CASTELL; BELKYS A. MALETTO; MORON VG; MARÍA C PISTORESI- PALENCIA

Mar del Plata

Congreso; LXIV Reunión de la Sociedad Argentina de Inmunología; 2016

Sociedad Argentina de Inmunolog

"Alike the aging microenvironment, tumor can be viewed as a""ronic inflammatory condition characterized by increased levels of""ch""pro-inflammatory cytokines as well as an overall immunosuppres- sive state. Previously we demonstrated that aged CpG-ODN+IFA treated mice present an expansion of myeloid derived suppressor cells (MDSC) capable of suppressing T-cell proliferative response. To characterize the effect of CpG-ODN+IFA in splenic MDSC in a tumor model, BALB/c young mice were injected with 4T1 mam- mary carcinoma into the mammary fat pads. CpG-ODN+IFA was injected  (s.c)  weekly,  starting  on  day  7.  We  observed  delayed tumor progression in CpG-ODN+IFA-treated tumor bearing mice (p�0.05). After 24 days of tumor growth there were no significant differences in CD11b+Gr1+ MDSC levels, although a lower frequen- cy  of  granulocytic  MDSC  (CD11b+Ly6G+Ly6Clow)  was  observed (p�0.05)  while  monocytic  MDSC  (CD11b+Ly6G-Ly6Chigh)  levels were  augmented  compared  to  non-treated  tumor  bearing  mice (p�0.05). In line with this, we also found reduced levels of reac- tive oxygen species (ROS) in total MDSC (p�0.05) and mainly in the granulocytic subset (p�0.01) of CpG-ODN+IFA-treated tumor bearing mice, but no significant differences were observed in nitric oxide (NO) production. In conclusion, systemic treatment of 4T1 tumor bearing young mice with CpG-ODN+IFA leads to a change in the composition of splenic MDSC subsets and these changes could be playing a role in the tumor progression."