TLR2 may influence the behavior of the malignant clone in B-CLL

Abstract B-cell receptor (BCR) and Toll-like receptor (TLR) stimulation and integration with signals from the pathogen or immune cells and their products determine the B-cell antibody response. Low expression of BCR is the hallmark of B lymphocytes in CLL, however little is known about the expression and function of TLR in B-CLL. We studied TLR2, TLR4, IL-6 and mIL-6Rα expression on mRNA and protein level in CD19 + subpopulation of normal lymphocytes and the CD19 + CD5 + subpopulation from B-CLL. Experiments were performed on unstimulated and stimulated lymphocytes [ Staphylococcus aureus Cowan I (SAC) and lipopolysaccharide (LPS) from Escherichia coli — TLR2- and TLR4-specific agonists, respectively]. We showed undetectable or low IL-6 expression, which seems to be specific for B-CLL lymphocytes. Induction of TLR4 mRNA upon LPS stimulation affected the expression of IL-6, but not of mIL-6Rα. Increased expression of TLR2 (MFI) after LPS and SAC stimulation did not correlate with mIL-6Rα receptor expression. B-CLL CD19 + CD5 + lymphocytes showed a significant increase in TLR2 expression at the protein level after stimulation with SAC and LPS compared to normal CD19 + lymphocytes. TLR2 may influence the behaviour of the malignant clone in B-CLL.