immunology of infectious and parasitic diseases - XXXVII Congress ...

Characterization of costimulatory molecules and inhibitory receptors during P.
vivax malaria
Pedro Carvalho Costa (PG), Fabiana M. Leoratti (P), Mauro Shugiro Tada (P),
Luis Hildebrando Pereira da Silva (P), Ricardo T. Gazzinelli (P), Lis R. V.
Antonelli (P)
Introduction: In Brazil, malaria is still a significant public health problem.
Although the numbers of malaria cases are decreasing, the incidence was
higher than 300,000 cases in the past two years. Of these cases, Plasmodium
vivax was found to be the causative agent in 90% of these cases (WHO Fact
Sheet, 2008; n° 94). The adaptive immune response, along with the
mechanisms of innate immunity, has the task of overcoming the strategies
imposed by infectious agents, leading to the control of the disease (Nat
Immunol. 9(7):725-32, 2008). It is know that T cell-mediated responses are
essential for parasite control; however the mechanisms behind this response
are not clear. The goal of this study is to assess the phenotype of T cells from
P. vivax-infected patient focusing on the expression of molecules such as T cell
immunoglobulin-3 (Tim-3), cytotoxic T lymphocyte attenuator (CTLA-4) and
programmed death 1 (PD-1).
Methods and Results: Peripheral blood mononuclear cells from P. vivax-
infected patients were obtained in Porto Velho; RO. Lymphocytes were
analyzed by flow cytometry. Our data show increased levels of inflammatory
cytokines and decreased absolute numbers of lymphocytes during acute
infection. Interestingly, the expression of costimulatory and inhibitory molecules
has been associated with impairment of T cell function during a variety of
infectious diseases. Accordingly, our data show that the above-mentioned
costimulatory and regulatory molecules are also upregulated on T cells from
malaria patients. The increased expression of some of these molecules
correlates with liver damage and platelets during acute P. vivax infection.