| Resumo: | Monoclonal gammopathies result from the proliferation of a single clone of plasma cells (PCs) and include disorders such as monoclonal gammopathy of undetermined significance (MGUS) and Multiple Myeloma (MM). It is speculated that the triggering event that turns healthy PCs into pathological PCs happens in the germinal centre (GC), most likely during a process known as somatic hypermutation (SHM), which takes place during antigen affinity maturation. GC maintenance, as well as, GC B-cell selection depends on T cell help, particularly on follicular T cells. In this study we aimed to analyse different T cell populations in the BM microenvironment of patients with monoclonal gammopathies, focusing on follicular-like T cells. Through multiparameter flow-cytometry we analysed CD4+, CD8+, γδ+, CD4-CD8- αβ+ and CD4+CD8+ T cells and identified follicular-like cells based on the expression of CXCR5, as well as activated T cells according to CD25 and HLA-DR expression, in all T cell subpopulations. We observed a general increase of follicular-like T cells in these patients, reaching statistical significance in the Th reg follicular-like cell subset when comparing the MM group with controls. The γδ+ follicular-like T subset was, however decreased in all MM groups. Interestingly, a decrease in activated follicular-like T cells was observed. In conclusion, despite of follicular-like T cells being increased in monoclonal gammopathy patients, they tend to less activated, which suggests that these cells are either not responding to the BM microenvironment or being negatively regulated. Our study population was small so further studies concerning follicular-like T cells in the BM of patients with monoclonal gammopathies may help understand the role of these cells in the BM microenvironment.
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