Altered surface expression patterns of circulating monocytes in cancer patients: impaired capacity of T-cell stimulation?

Philadelphia-negative myeloproliferative neoplasms display alterations in monocyte subpopulations frequency and immunophenotype

Philadelphia-negative myeloproliferative neoplasms (MPN) are clonal hematological diseases associated with driver mutations in JAK2, CALR, and MPL genes. Moreover, several evidence suggests that chronic inflammation and alterations in stromal and immune cells may contribute to MPN’s pathophysiology. We evaluated the frequency and the immunophenotype of peripheral blood monocyte subpopulations in patients with polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF). Peripheral blood monocytes from PV (n = 16), ET (n = 16), and MF (n = 15) patients and healthy donors (n = 10) were isolated and submitted to immunophenotyping to determine the frequency of monocyte subpopulations and surface markers expression density. Plasma samples were used to measure the levels of soluble CD163, a biomarker of monocyte activity. PV, ET, and MF patients presented increased frequency of intermediate and non-classical monocytes and reduced frequency of classical monocytes compared to controls. Positivity for JAK2 mutation was significantly associated with the percentage of intermediate monocytes. PV, ET, and MF patients presented high-activated monocytes, evidenced by higher HLA-DR expression and increased soluble CD163 levels. The three MPN categories presented increased frequency of CD56⁺ aberrant monocytes, and PV and ET patients presented reduced frequency of CD80/86⁺ monocytes. Therefore, alterations in monocyte subpopulations frequency and surface markers expression pattern may contribute to oncoinflammation and may be associated with the pathophysiology of MPN.

Impairment of lymphocyte function following yttrium-90 DOTATOC therapy

The radiolabeled somatostatin analogue, yttrium-90 DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC), is currently applied to treat advanced somatostatin receptor-positive tumors, e.g., neuroendocrine tumors of the pancreas, lung or gut. However, effects of this treatment on antimicrobial immune responses are not yet defined. In 20 patients treated with DOTATOC, cellular in vitro immune function was determined. Their antimicrobial lymphocyte responses were assessed by lymphocyte transformation test and enzyme-linked immunospot-measuring lymphocyte proliferation and on a single cell level production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin-10)-prior to therapy, at day 1, day 7 and day 90 post-therapy. Proliferative lymphocyte responses and interferon-γ production after in vitro stimulation with microbial antigens were non-significantly suppressed at day 1 and significantly (p < 0.05) at day 7 versus pre-therapy. In vitro immune responses did not fully recover until day 90. In contrast, at day 1 interleukin-10 production was significantly (p < 0.05) increased. Taken together, we observed a decrease in pro-inflammatory immune responses after DOTATOC therapy. Patients with versus without bone metastases displayed significantly (p < 0.05) lower cellular immune responses toward several microbial antigens. Progressive disease and higher tumor burden could also be defined as factors associated with impaired immune function. Spearman correlation analysis indicated that cellular in vitro immunity was positively correlated with kidney function; better kidney function led to stronger immune responses. In conclusion, DOTATOC therapy caused a decrease in in vitro immune responses against microorganisms. The clinical impact needs to be evaluated in further studies.

Types I and II interferons upregulate the costimulatory CD80 molecule in monocytes via interferon regulatory factor-1

CD80/B7.1 expressed on monocytes plays a prominent role in the activation of T cell-mediated immunity and its level is reduced in monocytes from cancer patients. Type I (alpha/beta) and type II (gamma) IFNs are widely administered as adjuvant therapy. We show here that both classes of IFNs upregulate CD80 mRNA and protein in primary monocytes ex vivo. The stimulatory action of IFN-alpha/beta on CD80 is accompanied by the activation of both interferon regulatory factors IRF-1 and IRF-7, whereas IFN-gamma stimulating effect is associated only with IRF-1 induction. IFNs concomitantly upregulate the transcription of CD40 costimulatory molecule whose activation is known to require IRF-1. In monocytic U937 cells, IRF-1 is activated by IFN-gamma but not by IFN-alpha/beta, whereas it is the reverse for IRF-7; in the latter cells, only IFN-gamma is capable of stimulating CD80 transcription emphasizing the essential role of IRF-1. Moreover, siRNA against IRF-1 prevents IFN-gamma-mediated CD80 activation. In AML cells, IFNs upregulate CD40, CD80 and IRF-1 in the FAB-M4/M5 subtypes but not in the less differentiated M1/M2 subtypes. Monitoring the expression of CD80 on AML cells and its modulation by IFNs could help to predict the patients more susceptible to benefit from therapeutic strategies aimed at eliciting specific T cell responses to leukemia-associated antigens.