Introduction:
This research aimed to study CD49d expression – a potential prognosis marker in chronic lymphocytic leukaemia (CLL) patients – at the protein and mRNA levels. It was analysed in terms of time to first treatment and compared to currently known prognostic markers and novel molecular markers.

Material and methods:
Using samples from 199 newly diagnosed CLL patients, we conducted immunophenotypical analyses of CD49d with flow cytometry, and assessed its expression on the mRNA level using quantitative polymerase chain reaction (PCR).

Results:
Cytometric analysis showed significantly higher expression of CD49d protein in ZAP-70+ (cut-off of 20%) patients than that in ZAP-70 patients (18.52 vs. 6.57, p = 0.028), and a tendency of higher CD49d expression in CD38+ patients than in CD38 patients (20.48 vs. 7.25, p = 0.072). CD49d expression significantly correlated with serum β2-microglobulin (r = 0.273, p = 0.012) and lactate dehydrogenase activity (r = 0.159, p < 0.01). Analysed in subgroups divided according to novel mutations, CD49d expression showed a tendency to be higher in MUT SF3B1 (93.98 vs. 7.86, p = 0.06) and MUT NOTCH1 (18.52 vs. 7.86, p = 0.140) groups than in the corresponding UNMUT groups. CD49d expression did not affect the time to first treatment at protein or mRNA level.

Conclusions:
High CD49d expression at the protein level accompanies aggressive biological markers in CLL patients, indicating its prognostic potential. It can thus be used to identify patients with poor clinical CLL prognosis.