As a crucial arm of innate immunity, the complement cascade (ComC) is involved both in mobilization of normal hematopoietic stem/progenitor cells (HSPCs) from bone marrow (BM) into peripheral blood (PB) and in their homing to BM. Despite the fact that ComC cleavage fragments alone do not chemoattract normal HSPCs, we found that leukemia cell lines as well as clonogenic blasts from CML and AML patients respond robustly to C3 and C5 cleavage fragments by chemotaxis and increased adhesion. This finding was supported by the detection of C3a and C5a receptors in cells from human malignant hematopoietic cell lines and patient blasts at the mRNA (RT-PCR) and protein level (FACS) and by the demonstration that these receptors respond to stimulation by C3a and C5a by phosphorylation of p42/44 and p38 MAPK and AKT. We also found that inducible heme oxygenase 1 (HO-1) is a negative regulator of ComC-mediated trafficking of leukemic cells and that stimulation of leukemic cells by C3 or C5 cleavage fragments activates p38 MAPK, which downregulates HO-1 expression, rendering cells more mobile. We conclude that activation of the ComC in leukemia/lymphoma patients (e.g., as a result of accompanying infections) enhances the motility of malignant cells and contributes to their spread in a p38 MAPK–HO-1-dependent manner. Therefore, inhibition of p38 MAPK or upregulation of HO-1 by small-molecule modulators would have a beneficial effect on ameliorating expansion of leukemia/lymphoma cells when the ComC becomes activated.

Tumour necrosis factor alpha (TNF-α) is an inflammatory cytokine with a wide spectrum of biological activity, including angiogenesis. B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are members of the TNF-α family. Vascular endothelial growth factor (VEGF), on the other hand, is one of the most characteristic pro-angiogenic cytokines produced by multiple cell types in multiple myeloma (MM). We have analysed BAFF and APRIL concentrations in parallel with pro-angiogenic cytokines in serum and trephine biopsy, and the bone marrow microvascular density (MVD) in 50 patients with newly diagnosed IgG MM and 24 healthy volunteers. The study showed statistically higher concentrations of BAFF, APRIL and TNF-α, as well as VEGF and its receptor, in MM patients compared to healthy volunteers and patients in advanced stages of the disease. A statistically positive correlation between the concentration of TNF-α and the expression of VEGF was demonstrated, and so was a positive link between BAFF, APRIL, MVD and lactate dehydrogenase (LDH). Furthermore, we observed a significant decrease in all studied cytokines after anti-angiogenic therapy, with meaningful differences between responders (at least partial remission) and patients with stable disease. It was also established that APRIL, but not BAFF, correlated with pro-angiogenic cytokines such as VEGF with its receptor, MVD and syndecan-1. Finally, our results showed that serum BAFF and APRIL levels could be useful biomarkers of MM disease activity and its progression which suggests that APRIL could be a possible novel therapeutic target in MM.

Drugs targeting immune checkpoint molecules have been found effective in melanoma, lung cancer, and other malignancies treatment. Recent studies on breast cancer demonstrated the significance of inhibitory anti-CTLA-4 and anti-PD-1 in the regulation of disease progression. However, seemingly the same types of breast cancer do not always respond unambiguously to immunotherapy. Thus, here we set out to analyze the in vitro effects of inhibiting CTLA-4 and PD-1 on interactions between co-cultured lymphocytes and two selected breast adenocarcinoma cell lines. Breast cancer cells were co-cultured with lymphocytes to evaluate the effects of CTLA-4 and PD-1 inhibition. Proliferation, cell cycle, and viability assessment were measured in cancer cells. IFN-gamma, IL-10, perforin, granzyme B production, and CTLA-4 and PD-1 expression were analyzed in lymphocytes. We found that administration of anti-CTLA-4 improved the anti-cancer activity of T cells with reduced proliferation and viability of MDA-MB-231. Lack of response was observed in the context of MCF-7. In addition, differential expression of checkpoint proteins was found between studied cancer cells lines. Inhibition of molecules was followed by IL-10 and IFN-gamma decrease in lymphocytes co-cultured with MDA-MB-231, not demonstrated in reference to MCF-7. Furthermore, CTLA-4 blockage was associated with reduction of CTLA-4+ and PD-1+ lymphocytes in MDA-MB-231, with a significant increase in MCF-7, reduced by anti-PD-1. Altogether, our study revealed that anti-CTLA-4 and anti-PD-1 treatment can improve lymphocytes effects on breast cancer cells. Favorable effects seemed to be related to breast cancer cells features as differential responses were reported. Novel blocking antibodies strategies should be tested for more effective cancer inhibition.

Recent studies in a mouse model of chronic lymphocytic leukemia (CLL) demonstrated that inhibition of the programmed death receptor 1 (PD‑1)-PD‑L1 axis resulted in correction of leukemia‑induced CD8+ T cell‑related immune dysfunction and protected mice against CLL development. However, it remains unclear whether CLL development and progression can be also associated with CD4+ T cells expressing PD‑1. We aimed to analyze whether a quantitative assessment of CD4+PD‑1+ T cells performed at the time of diagnosis can have prognostic significance in patients with CLL. We examined 56 patients with newly diagnosed CLL at different stages of the disease. The quantitative assessment of PD‑1‑expressing CD4+ T cells was performed in all patients, using multicolor flow cytometry. We demonstrated that CLL patients with an advanced (high and intermediate risk) stage had a significantly higher number of CD4+PD‑1+ T cells compared with subjects with low‑grade disease. Importantly, we showed that the number of PD‑1‑expressing CD4+ T cells in the peripheral blood of patients referred for immediate treatment due to the advanced stage of the disease was significantly higher compared with subjects on watchful waiting. Finally, we found that treatment‑naive patients with higher numbers of CD4+PD‑1+ T cells at baseline showed a significantly shortened time to the first treatment compared with patients with a low number of CD4+PD‑1+ T cells. Our study showed that the quantative assessment of CD4+PD‑1+ T cells in peripheral blood using flow cytometry can facilitate prognostication of patients with newly diagnosed CLL.