MEC1 and MEC2: Two new cell lines derived from B-chronic lymphocytic leukaemia in prolymphocytoid transformation

Alessandra Stacchini, Michela Aragno, Antonella Vallario, Alda Alfarano, Paola Circosta, Daniela Gottardi, Alessandra Faldella, Giovanna Rege-Cambrin, Ulf Thunberg, Kenneth Nilsson, Federico Caligaris-Cappio

Research output: Contribution to journalArticlepeer-review


We report the establishment and characterization of two cell lines, MEC1 and MEC2, that grew spontaneously on two subsequent occasions from the peripheral blood (PB) of a patient with B-chronic lymphocytic leukemia (B- CLL) in prolymphocytoid transformation. The patient was EBV-seropositive, his leukemic cells were EBNA negative, but the spontaneously grown cell lines are EBNA-2 positive. In liquid culture MEC1 cells grow adherent to the vessel wall and as tiny clumps; MEC2 cells do not adhere and form large clumps. The doubling time of MEC1 is 40h and of MEC2 is 31h. Both cell lines express the same light (κ) and heavy chains (μ, δ) as the fresh parental B-CLL cells at the same high intensity, share the expression of mature B cell markers (CD19, CD20, CD21, CD22), differ in the expression of CD23 and FMC7, are CD11a+, CD18+, CD44+, CD49d+, CD54+ and express at high levels both CD80 and CD86. CD5 is negative on MEC1 cells (as on the vast majority of parental cells) and it has been lost by MEC2 cells after several months of culture. The cells have a complex karyotype. The tumour origin of MEC1 and MEC2 has been demonstrated by Southern blot analysis of the IgH loci and by Ig gene DNA sequencing. They use the VH4 Ig family and have not undergone somatic mutations (94.8% homology with germline Ig gene 4-59). Cytofluorographic analysis and RT-PCR reveal that MEC1 and MEC2 overexpress Bcl-2 together with Bax, express large amounts of Bcl-xL and trace amounts of Bcl-xS.

Original languageEnglish
Pages (from-to)127-136
Number of pages10
JournalLeukemia Research
Issue number2
Publication statusPublished - Feb 1999


  • Apoptosis
  • B-chronic lymphocytic leukemia
  • Bcl- 2
  • Cell lines
  • Epstein-Barr virus
  • Prolymphocytic leukemia

ASJC Scopus subject areas

  • Cancer Research
  • Hematology
  • Oncology


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