Reduced Percentage of CD14dimCD16+SLAN+ Monocytes Producing TNF and IL-12 as an Immunological Sign of CLL Progression

Monocytes are one of the least studied immune cells with a potentially important role in the pathogenesis of chronic lymphocytic leukemia (CLL). Nevertheless, data regarding the role of subpopulations of monocytes in the CLL microenvironment are still limited. For the very first time, this study presents an assessment of monocyte subsets divided according to SLAN and CD16 expression in CLL patients. The study involved 70 freshly diagnosed CLL patients and 35 healthy donors. Using flow cytometry, monocyte subpopulations were assessed among PBMCs. CD14(+) monocytes can be divided into: classical (CD14(+)CD16(-)SLAN(-)), intermediate (CD14(+)CD16(+)SLAN(-)) and non-classical (CD14(dim)CD16(+)SLAN(+)). In our study, we noted an increased percentage of non-classical monocytes with intracellular expression of TNF and IL-12. On the other hand, among the intermediate monocytes, a significantly higher percentage of cells synthesizing anti-inflammatory IL-10 was detected. The percentage of CD14(dim)CD16(+)SLAN(+) monocytes producing TNF and IL-12 decreased with the stage of CLL and inversely correlated with the expression of the prognostic factors ZAP-70 and CD38. Moreover, the percentage of CD14(dim)CD16(+)SLAN(+) monocytes producing TNF and IL-12 was lower in CLL patients requiring treatment. This may indicate the beneficial effect of non-classical monocytes on the anti-tumor response.

Automated summary

Monocytes, particularly non-classical subpopulations, may play an important role in chronic lymphocytic leukemia (CLL) pathogenesis. This study assessed monocyte subsets divided based on SLAN and CD16 expression in CLL patients. The findings suggest an increased percentage of non-classical monocytes producing TNF and IL-12, while intermediate monocytes showed a higher percentage of cells synthesizing anti-inflammatory IL-10. The percentage of CD14(dim)CD16(+)SLAN(+) monocytes producing TNF and IL-12 decreased with CLL stage and correlated with prognostic factors. Notably, CLL patients requiring treatment had a lower percentage of CD14(dim)CD16(+)SLAN(+) monocytes producing TNF and IL-12, potentially indicating a beneficial effect of non-classical monocytes on anti-tumor response.