Aims Diffuse large B-cell lymphoma (DLBCL) is characterised by marked clinical and biological heterogeneity, attributable to the tumour cells and their microenvironment.

Methods In this study, we investigated circulating subsets of blood lymphocytes and monocytes and their relationship with T cells in the tumour microenvironment (TME) in chemoresistant and chemosensitive patients with DLBCL.

Results The study showed that (1) absolute lymphocyte count (ALC) and CD3+ and CD4+ cells were reduced in chemoresistant patients compared with chemosensitive patients; (2) lymphocyte:monocyte ratio (LMR) showed a positive correlation with peripheral blood CD3+ and CD4+ cells; (3) ALC, LMR, peripheral blood CD3+ and CD4+ cells showed a positive correlation with T cells in the TME.

Conclusions Overall, these data suggest that DLBCL with high TME T cells display a pre-existing antitumour immune response. In the rituximab-containing regimen, TME T cells are stimulated further to participate in the immune response against lymphoma cells. In contrast, DLBCL lymphomas with low T-cell infiltration reflect the absence of a pre-existing antitumour immunity and have a lower likelihood of obtaining an optimal response to therapy.