Risk factors in chronic lymphocytic leukemia, validation of flow cytometric detection using RT-PCR and immunohistochemistry
Abstract
Individual prognosis in patients with chronic lymphocytic leukemia (CLL) may be specified by biological risk factors, detection of which must however be sufficiently standardized prior to their introduction into clinical practice. In the presented study of 73 patients we have assessed immunoglobulin variable heavy-chain gene (IgVH) status, presence of mutation in p53 gene and with the use of flow cytometry (FCM) expression of CD38 and ZAP-70 tyrosine kinase.
Unmutated IgVH status was present in 58 % patients, p53 mutation in 19 %, positive expression of CD38 in 26 % and positive expression of ZAP-70 using FCM in 62 %. Patients with unmutated IgVH, positive expression of ZAP-70 assessed by FCM and p53 mutation had significantly shorter time from diagnosis to initiation of therapy.
Overall concordance between ZAP-70 expression and IgVH mutational status was 85 %. Validation of the FCM ZAP-70 detection was performed by comparison to the immunohistochemical analysis on histological sections and quantitative real-time PCR on the mRNA level; overall concordance was 86 %.
Expression of ZAP-70 showed to be stable over time; with median time of 12 months from the acquisition of the first sample to the last, qualitative change of ZAP-70 expression was noted in only one patient, who became positive upon disease progression.