The 14q+ marker in hairy cell leukaemia. A cytogenetic study of 15 cases

Leukaemic cells from 19 patients with hairy cell leukaemia (HCL), characterised by morphological, immunological and ultrastructural criteria, were investigated for chromosome abnormalities after stimulation with B-cell mitogens (Pokeweed mitogen (PWM), lipopolysaccharide B and EBV). The cells from all cases had a B-cell phenotype and in each case only a single light chain type was expressed on the membrane of the cells. Only 15 patients with adequate metaphases are included in this study. Clonal chromosome abnormalities were observed in 12 patients of which five had a 14q + involving q32. Of the remaining 3 cases 1 had nonclonal abnormalities and 2 had normal karyotypes. The donor chromosomes were identified in 3 cases and were found to be 9, 18 and 22. An interstitial rearrangement of chromosome 14 involving band q22 was seen in 2 cases and a deletion of chromosome 14 at q24 in 1 case. Amongst other chromosome abnormalities 12p was involved in 4 cases, 12q in 2 cases and chromosomes 7 and 22 in 3 cases each. The significance of the abnormalities has been discussed in relation to sites of cellular oncogenes. Our study demonstrates that chromosome abnormalities common to other B-cell disorders are present in HCL.