Análise da resposta imune citotóxica de linfócitos T CD8+ e células NK de pacientes com linfoma não-Hodgkin e mieloma múltiplo

Abstract

Cytotoxic T lymphocytes (LTCs) and natural killer cells (NK) are responsible for defending against tumor cells and share the perforin and granzymes-mediated death pathway as one of their major cytotoxic mechanisms. This study aimed to identify polymorphisms in the perforin gene (PRF1) and to quantify perforin and granzyme B gene and protein expression levels in patients with non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM).The results concerning the expression of these proteins were correlated with patient survival and the functional analysis of the non-synonymous polymorphisms in homozygotes was performed. We did not observe differences between the frequency of polymorphisms in the coding region of the PRF1 gene of patients with NHL and MM compared to healthy individuals. However, the greater gene expression of perforin and granzyme B was associated with longer survival of patients with MM and NHL. Regarding the lymphocyte profile in the peripheral blood, we observed that NHL patients had a higher number of activated CTLs that expressed perforin, however, the intracellular quantification of perforin in NK cells was significantly reduced compared to healthy individuals. MM patients had a higher number of perforin and granzyme B-expressing CTLs, and although there was an increase in the percentage of NK cells compared to healthy individuals, no differences were observed regarding the amount of NK cells expressing perforin and granzyme B in patients with MM and healthy individuals. There was no significant difference between the frequency of polymorphisms in the PRF1 coding region of patients with NHL and MM compared to the control group; however, higher gene expression of perforin and granzyme B was associated with longer survival of patients with MM and NHL. Although not statistically different, the frequency of A91V polymorphism in MM patients was more than double the frequency found in healthy subjects. We believe that a future study with a larger number of patients is needed to better clarify the association of this polymorphism with MM. Only one patient with MM was identified as homozygous for a non-synonymous mutation. This patient was carrying the A91V polymorphism and its effector cells showed significantly reduced ability to induce specific lysis of a K562 tumor line. We also observed that this patient has had reduced intracellular perforin levels in NK cell granules. Considering these results, we believe that the gene expression of perforin and granzyme B may be potential prognostic markers in NHL and MM.