Full text
| |
| Author(s): |
Adriana Coutinho Borgo
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2010-03-01 |
| Examining board members: |
Simone Gonçalves da Fonseca;
Ises de Almeida Abrahamsohn;
Myrthes Anna Maragna Toledo Barros;
Mauricio Martins Rodrigues;
Reinaldo Salomão
|
| Advisor: | Simone Gonçalves da Fonseca |
| Abstract | |
The persistence of functional memory T cell is important to ensure a protective immunity to Human Immunodeficiency Virus (HIV) infection. Memory T cells have been subdivided into central memory (TCM), effector memory (TEM) and highly differentiated effector memory (TEMRA) based on the expression of surface molecules such as CCR7 and CD45RA, and the ability to produce cytokines and proliferate. Recently, we identified 18 peptides derived from B consensus sequences of HIV-1 that bind to multiple HLA-DR molecules and are widely recognized by peripheral blood T lymphocytes from HIV-infected patients. Given this and considering the importance of memory T cells in the maintenance of specific immune response, our objective was to characterize phenotypic and functionally memory T cell subsets from HIV-infected individuals involved in the recognition of these epitopes in vitro. The study included 14 healthy control subjects and 61 HIV+ patients with CD4+ lymphocytes counts higher than 250 cells/mm3. The HIV+ patients were divided into six different clinical groups according to the stage of infection, plasma viral load (VL) and antiretroviral therapy use (ART): long-term non-progressors (LTNP), aviremic under ART (AV-ART), viremic under ART (VI-ART), viremic without using ART (VI without ART), recently infected viremic without using ART (VI-RI) and controllers. Peripheral blood mononuclear cells from study subjects were stimulated with HIV-1 peptide pool and with a cytomegalovirus (CMV) peptide pool. The frequencies of IFN- and IL-2 producing memory cells and antigenspecific cell proliferation were detected by multiparametric flow cytometry. Our results showed that the HIV-1 set of peptides was able to activate TCM, TEM and TEMRA functional memory subsets that secrete IFN- and IL-2 in 100% of the HIV patients from the different clinical groups. The HIV-1 set of peptides also induced memory T lymphocyte subsets proliferation. TEMRA CD4+IFN-+, total TEMRA CD4+IFN-+, TCM CD8+IFN-+, total TCM CD8+IFN-+, total TEM CD8+IFN-+, TEM CD8+IFN-+ and TEMRA CD8+IFN- + frequencies negatively correlated with HIV viral load in viremic patients. These data suggest that these functional memory subsets are important to control the viremia. When comparing the HIV and CMV-specific responses we observed higher frequencies of IL-2, IFN-/IL-2 and IFN- producing memory T cells in response to HIV peptide pool. These data suggest that this set of HIV sequence derived peptides activates polyfunctional response of memory T lymphocyte subsets. Our results showed that the HIV-1 peptide set was able to stimulate different IFN-, IFN-/IL-2 e IL-2 producing memory T lymphocytes from individuals in different stages of HIV infection and suggest the involvement of functional memory subsets in the control of viremia. These findings strengthen the possibility of using these peptides in a successful vaccine formulation in humans (AU) | |