The effect of IL-4 on CD180 expression and signalling in Chronic lymphocytic leukaemia (CLL).

Chronic lymphocytic leukaemia (CLL) progression is critically dependent on tumour microenvironment (TME) signals, including those regulated via toll-like receptors (TLRs) that drive CLL cell survival and proliferation. We have previously shown that CD180, an orphan TLR is expressed on the surface in approximately 60 % of CLL samples, and that heterogeneity of CD180 cell surface expression and signalling impacts CLL cell survival, proliferation, and apoptosis. Interleukin-4 (IL-4), a cytokine abundantly present in the CLL microenvironment, is a well-documented pro-survival factor for CLL cells. IL-4 has also been shown to enhance sIgM expression and function by subsequent downstream signalling in a JAK3/STAT6 dependent manner within CLL samples. In this study, we investigated the impact of IL-4 on CD180 expression, CD180-mediated signalling and apoptosis of CLL cells and cell lines MEC-1 and RAMOS. Our results demonstrate that IL-4 enhances CD180 surface expression in CLL cells and RAMOS cell line, affecting downstream signalling pathways that alter CLL cell survival through the activation of AKT and p38MAPK. MEC-1 cells exhibited a less pronounced and variable response. These findings highlight the IL-4/CD180 axis as an important modulator of CLL, altering cell signalling dynamics.