Toll like Receptors (TLRs) in B Cell Chronic Lymphocytic Leukemia (B-CLL).

Introduction: B-CLL is characterised by the accumulation of long-lived CD5⁺ B cells. Mature B cells can be activated via TLRs to produce immunoglobulin and proliferate. We have previously reported differential surface expression of CD180, TLR-4 associated receptor, by B-CLL cells in relation to IgVh gene status (

Method: B cells from untreated (n=24) and treated (CHOP n=3, Thalidomide n=1 and chlorambucil and prednisolone n=2) CLL patients, and healthy aged matched controls, (n=14) were isolated by CD19⁺ selection using iMACs columns (Miltenyi Biotec), total RNA extracted (Qiagen) and primers for TLR2, TLR4, TLR9, CD180 and the adaptor protein MYD88 were used for TaqMan PCR analysis (ABI). GAPDH was used for normalization. Data were expressed as mean delta cycle number (ct) ± standard deviation, giving a value inversely related to the level of expression of the specific gene. Patients were separated into groups according to IgVh gene mutation status or level of Zap 70 expression. Statistical analysis was performed using by Mann-Whitney U test and Spearman rank correlation or Pearson’s correlation coefficient.

Results: Overall, there was a heterogeneous pattern of TLR expression in patients and controls with no significant differences between them. Treated patients were characterised by higher mRNA levels for the all TLRs measured (TLR9 p=0.018) and MYD88 (MYD88 p=0.026) compared with untreated patients, despite no significant difference of their GAPDH levels (p>0.05). Significant correlations were seen between mRNA levels for the TLRs within the age matched control group (all p<0.05). Groups of patients were further analysed according to mutated (mutated >2%) or unmutated IgVh genes (unmutated <2%). No significant correlation in the TLR expression levels was found within the mutated patient group (n=8) or Zap 70 ^low expression group (<0.7 level) (n=11). Preliminary data from patients with an unmutated IgVh gene status (n=4) or according to levels of ZAP 70^high expression (n=5) showed correlation of mRNA levels for TLRs and MYD88 expression (all p<0.05).

Conclusion: Our data indicates a direct relationship between MYD88 and TLRs transcription levels in healthy control individuals. Lack of significant correlation amongst TLR mRNA levels in CLL patients with mutated IgVh genes and Zap70^low expression levels suggests aberrant regulation of TLRs in this group.