A novel natural killer cell line (KHYG-1) from a patient with aggressive natural killer cell leukemia carrying a p53 point mutation

We present the establishment of a natural killer (NK) leukemia cell line, d esignated KHYG-1, from the blood of a patient with aggressive NK leukemia, which both possessed the same p53 point mutation. The immunophenotype of th e primary leukemia cells was CD2(+), surface CD3(-), cytoplasmic CD3 epsilo n(+), CD7(+), CD8 alpha alpha(+), CD16(+), CD56(+), CD57(+) and HLA-DR+. A new cell line (KHYG-1) was established by culturing peripheral leukemia cel ls with 100 units of recombinant interleukin (IL)-2. The KHYG-1 cells showe d LGL morphology with a large nucleus, coarse chromatin, conspicuous nucleo li, and abundant basophilic cytoplasm with many azurophilic granules. The i mmunophenotype of KHYG-1 cells was CD1(-), CD2(+), surface CD3(-), cytoplas mic CD3 epsilon(+), CD7(+), CD8 alpha alpha(+), CD16(-), CD25(-), CD33(+), CD34(-), CD56(+) CD57(-), CD122(+), CD132(+), and TdT(-). Southern blot ana lysis of these cells revealed a normal germline configuration for the beta, delta, and gamma chains of the T cell receptor and the immunoglobulin heav y-chain genes. Moreover, the KHYG-1 cells displayed NK cell activity and IL -2-dependent proliferation in vitro, suggesting that they are of NK cell or igin. Epstein-Barr virus (EBV) DNA was not detected in KHYG-1 cells by Sout hern blot analysis with a terminal repeat probe from an EBV genome. A point mutation in exon 7 of the p53 gene was detected in the KHYG-1 cells by PCR /SSCP analysis, and direct sequencing revealed the conversion of C to T at nucleotide 877 in codon 248. The primary leukemia cells also carried the sa me point mutation. Although the precise role of the p53 point mutation in l eukemogenesis remains to be clarified, the establishment of an NK leukemia cell line with a p53 point mutation could be valuable in the study of leuke mogenesis.