KINETIC AND SUPPRESSOR FUNCTION OF CD11b+ GR-1+ SPLENOCYTES IN THE PRECLINICAL ASSESSMENT OF THE TSf-ISPA VACCINE AGAINST TRYPANOSOMA CRUZI

GAMBA, JUAN CRUZ; BORGNA, ELIANA; ARIAS, DIEGO; VERMEULEN, MÓNICA; CABRERA G.; MARCIPAR, I.; PROCHETTO, E.; PACINI, M. F.; PÉREZ, A. R.

Mar del plata

Congreso; REUNIÓN CONJUNTA SAIC SAI&FAIC SAFIS 2022; 2022

Sociedad Argentina de Inmunología

Introduction: We have previously reported that a vaccine based on a trans-sialidase fragment (TSf) formulated with a cage-like particle adjuvant (ISPA) protects BALB/c mice against Trypanosoma cruzi (T. cruzi) infection. Alterations of CD11b+Gr-1+ (Ly6G+/Ly6C+) cells, with a phenotype compatible with myeloid-derived suppressor cells (MDSCs), were observed during both the immunization and the acute phase of infection.Aim: To study the kinetic and suppressor function of CD11b+ Gr-1+ splenocytes in the preclinical assessment of the TSf-ISPA vaccine against T. cruzi.Methods: 3 doses of TSf-ISPA were given to BALB/c mice. For the challenge, immunized mice were intraperitoneally infected with 1000 T. cruzi (Tulahuen strain). Flow cytometry was used to measure CD11b+ GR-1+ splenocytes at days 2, 7 and 15 post-immunization (p.imm.), and at days 15 and 21 post-infection (p.i.). Magnetic cell sorting was used to purify Gr-1+ cells. Suppressive capacity of purified cells was assessed in vitro by measuring the inhibition of proliferation of responder cells labelled with 5,6-carboxifluorescein diacetate succinimidyl ester (CFSE). Results: CD11b+GR-1+ splenocytes increased p.imm. For instance, at day 7 p.imm. the mean number of CD11b+GR-1+ cells x106 ±standard deviation (SD) in PBS-treated mice was 1,4±0,1 vs 4,1±0,6 in TSf-ISPA mice (p