ATM is usually rearranged in T-cell prolymphocytic leukaemia

T-prolymphocytic leukaemia (T-PLL) is a rare, sporadic leukaemia similar to a mature T-cell leukaemia seen in some patients with Ataxia Telangiectasia (A-T), a recessive multisystem disorder caused by mutations of the ATM gene at chromosome 11q23. ATM sequence mutations have been reported in 46% of T-PLL cases, but some cases also have karyotypic abnormalities at 11q, including 11q23. This led us to investigate the structure of the ATM locus in a panel of eight cases, two of which had 11q23 abnormalities. As expected, nucleotide changes were detected in some samples. Two remission samples were wild type. To test for structural lesions, DNA fibres were hybridized with a contig of four labelled cosmids spanning the ATM locus. In all samples there were structural lesions and in four samples both alleles were affected. This provides strong evidence for our suggestion that ATM acts as a tumour suppressor during T-PLL tumorigenesis. Some additional role for ATM during T-PLL tumorigenesis is possible since nucleotide changes were present in addition to structural lesions disrupting both alleles. The mechanism of inactivation appeared to be unusual because multiple structural lesions on one allele were often observed.

The impact of molecular cytogenetics on chronic lymphoid leukaemia

Chronic lymphoid leukaemias are clonal expansions of B and T cells with mature membrane phenotype. Cytogenetic study of these cases usually requires mitogenic stimulation and can often be hindered by a lack of response of the tumour cells to mitogen, poor quality metaphases, complex markers and proliferation of normal cells. In situ hybridisation with fluorescence-labelled chromosome-specific centromeric DNA probe, single or low copy sequences and whole chromosome paints which hybridise to complementary sequences allow the detection of numerical and structural abnormalities on metaphase and interphase cells with much greater efficiency. Comparative genomic hybridisation uses whole genomic tumour DNA as probe which is hybridised to normal metaphases. It is particularly useful for detecting chromosomal changes without being dependent on the dividing tumour cells. The application of these techniques to the investigation of chronic lymphoid leukaemias is reviewed with emphasis on the work done in our laboratory on trisomy 12 and the tumour suppressor region 13q14 in chronic lymphocytic leukaemia, translocation t(11;14) (q13;q32) in mantle cell lymphoma and other chronic B cell leukaemias, inv(14) (q11q32), i(8q) and complex markers in T prolymphocytic leukaemia.

Sezary cell leukaemia: a distinct T cell disorder or a variant form of T prolymphocytic leukaemia?

We report the clinical, ultrastructural, immunophenotypic and virological features of nine cases of a rare type of mature T cell disorder formerly designated Sezary cell leukaemia. All patients presented with lymphocytosis ranging from 12.7 to 133 x 10(9)/l, bone marrow infiltration, splenomegaly and lymphadenopathy. Skin involvement was absent at presentation but developed as a terminal event in two patients, one of whom showed a pattern of dermal infiltration different from that characteristic of Sezary syndrome. Cells from eight cases bore a mature T cell phenotype and electronmicroscopy revealed lymphocytes with cerebriform nuclei resembling Sezary cells. All cases except one were HTLV-I negative. Patients were treated with various chemotherapy regimens but with poor outcome, the median survival being 13 months. Laboratory and clinical data suggest great similarity between Sezary cell leukaemia and T prolymphocytic leukaemia (T-PLL), namely coexpression of CD4 and CD8 (3/9 cases), identical chromosomal abnormalities in the three cases studied (isochromosome 8q plus inversion 14 or t(X;14)(q28;q11)) and a remarkable sensitivity to CAMPATH-1H (complete remission of 21 months' duration in one patient), suggesting that this entity could be considered a variant form of T-PLL. The alternative diagnosis of adult T cell leukaemia/lymphoma could not be excluded in one patient in whom positive HTLV-I serology was documented.

Two unbalanced translocations, t(12;22)(p13;q11) and t(12;?)(p13;?), in an aggressive chronic B-cell leukemia: TEL gene analysis using FISH

The translocation t(12;22)(p13;q11) has been consistently described in myeloid malignancies and shown to result from a fusion between the TEL and MN1 genes. Previously described deletions of 12p in acute lymphoblastic leukemias have been recently shown to harbor undetected translocations involving the TEL gene at 12p13. We document a case of an aggressive chronic B-cell leukemia whose cells had trisomy 12 and two unbalanced translocations involving 12p13, including a t(12;22)(p13;q11) as shown by conventional cytogenetics and fluorescence in situ hybridization (FISH). The 12p13 breakpoint of the t(12;22)(p13;q11) was telomeric to the TEL gene, and the second unbalanced translocation with breakpoint 12p13 resulted in the deletion of TEL. This case demonstrates that TEL gene deletions may be relevant in cases of mature B-lymphoproliferative diseases.

Relationship of T leukaemias with cerebriform nuclei to T-prolymphocytic leukaemia: a cytogenetic analysis with in situ hybridization

Sezary cell leukaemia (SCL) is a mature T-cell leukaemia with characteristic cerebriform nuclei, whereas Sezary syndrome (SS) involves a mature T-cell lymphoma with a similar nuclear morphology. We have examined these diseases by cytogenetics chromosome painting and fluorescence in situ hybridization (FISH). Both diseases had complex cytogenetic abnormalities. All three cases of SCL investigated had inv(14)(q11:q32) and two had iso(8q). No case of SS had these abnormalities but, instead, iso(17q) or 17p+ was present in the three cases of SS investigated and FISH indicated loss of heterozygosity due to deletion of a region at 17p 13 that included the tumour suppressor gene P53, implicating it in this malignancy. One case of SCL had iso(17q). The abnormalities of chromosomes 8 and 14 in SCL are commonly observed in T-prolymphocytic leukaemia (T-PLL) and suggest that SCL may be a variant of T-PLL rather than of SS.

The ultrastructure of mantle cell lymphoma and other B-cell disorders with translocation t(11;14)(q13;q32)

We conducted an ultrastructural study in 22 cases of B-lymphoproliferative disorders in leukaemic phase bearing the t(11;14) translocation. The features of peripheral blood leukaemic cells in nine cases of mantle cell lymphoma (MCL) were compared to those diagnosed as B-prolymphocytic leukaemia (B-PLL) (five cases), splenic lymphoma with villous lymphocytes (SLVL) (four cases), lymphoplasmocytic lymphoma (LPL) (one case), chronic lymphocytic leukaemia with > 10% prolymphocytes (CLL/ PL) (one case) and unclassified B-non Hodgkin's lymphoma (B-NHL) (two cases). The ultrastructural characteristics were also compared to those present in B-NHL without t(11;14), including cases of follicular centre lymphoma (FCL). This study shows that MCL has distinct ultrastructural features including a cleaved or indented nucleus with an even heterochromatin distribution, an absent or inconspicuous nucleolus, low N/C ratio, abundant mitochondria, a well developed Golgi zone, profiles of endoplasmic reticulum and centrioles. This pattern clearly differs from that found in FCL cells. The nuclear pattern of MCL cells also differed from the cells in the other disorders with t(11;14), but shared an organelle-rich cytoplasm, and features which were not apparent in cases without t(11;14). The cytoplasmic changes observed in cells bearing t(11;14) suggest increased cellular activity which may relate to the chromosome translocation and the resulting over-expression of bcl-1.

Expression of c-myc oncoprotein in chronic T cell leukemias

T cell clones in patients with ataxia telangiectasia (AT) and T cell prolymphocytic leukemia (T-PLL) have identical chromosome abnormalities, namely inv(14)(q11q32), t(14;14)(q11;q32) and t(X;14)(q27;q11). In T-PLL and AT developing T cell leukemia, the above abnormalities occur frequently together with trisomy for 8q. We postulated that the additional abnormalities of chromosome 8, where the c-myc oncogene is mapped to 8q24, may play a role in the development of overt leukemia. DNA analysis using the CD1A c-myc probe did not reveal rearrangements of the c-myc gene by Southern blotting. We have used a monoclonal antibody for the c-myc protein to investigate the level of expression in 11 patients with T-PLL and two with Sezary cell leukemia and compared it with levels seen in normal lymphocytes. Significantly higher levels were observed in patients compared with controls (P < 0.0001). The highest levels of c-myc were seen in eight cases with trisomy for 8q resulting from an i(8q). One patient was investigated before and after treatment. In the active state, c-myc showed a level of 64.36 units (range 20-200). After treatment a residual population of malignant cells showed a c-myc level of 155 (range 90-280). This study suggests that the increased expression of c-myc as a result of trisomy for 8q may have a role in the pathogenesis of de novo T-PLL and T cell leukemia supervening AT and that there may be a correlation between c-myc levels and resistance to therapy.

Cytogenetic abnormalities in the leukemic phase of non-Hodgkin lymphoma

We have carried out chromosome analysis in a series of 16 non-Hodgkin Lymphoma (NHL) cases in leukemic phase. The diagnoses in these patients based on histology and immunologic markers were as follows: follicular lymphoma (FL), 3 cases; mantle cell lymphoma (Mc), 4 cases; lymphoplasmacytic lymphoma (LPL), 8 cases, and large cell lymphoma, 1 case. We have shown that the t(14;18), t(11;14), and trisomy 12 retained their subtype association with FL, Mc, and LPL, respectively, as in their nonleukemic counterparts with one case of FL showing t(1;19)(q23;p13). Among the four LPL cases without trisomy 12, one case each showed t(12;14)(q13;q32), trisomy 14, t(1;3)(p34;q21), and del(3)(q21). The t(1;19) and t(12;14) may represent rare events in FL and LPL, respectively, and may be uniquely associated with the leukemic phase. The breakpoint 14q32 was the most common single breakpoint involved, sometimes involving both chromosome 14 homologues depicting its association with primary and secondary genetic events in the disease progression. In addition to the main abnormalities, we have shown additional complex abnormalities in 14 of 16 cases. Among these, chromosome 3 was the most commonly involved, affecting the short or long arm or the whole chromosome; 5 of the 16 cases involved breakpoint 3q21. The high incidence of additional abnormalities in these NHL in leukemic phase suggest an association with the development of leukemia and progression of the disease.

Chromosome abnormalities in hairy cell leukaemia variant

We describe chromosome abnormalities in 6 patients with hairy cell leukaemia (HCL) variant, a rare B-cell disorder with clinical and laboratory features intermediate between HCL and B-prolymphocytic leukaemia (B-PLL). All but one had marked splenomegaly and a raised white blood cell count (median 40 x 10(9)/l) with over 80% nucleolated hairy cells. These cells had a B-cell immunophenotype distinct from that of typical HCL. All patients but one are alive with stable disease with a median follow-up of 60 months. Numerical chromosome changes included loss of chromosomes 2, 3, 4, 6, 10, 19, 21, and X. three cases had translocations involving the immunoglobulin gene regions: t(14;17)(q32;q11), t(14;22)(q32;q11), and t(2;8)(p11.12;q24). Immunocytochemistry demonstrated the presence of the MYC protein in cells from the case with t(2;8) but not in two others. Other structural abnormalities included t(3;10)(q27;q22) and t(3;12)(q27;q13) in the same patient, der(17)t(7;10;17)(p11;q27;q22), t(1;3)(q25;p21), t(8;21)(p12;q11), t(17;21)(p11;p11), del(6)(q15), del(7)(q34), and del(14)(q24).

Splenic lymphoma with villous lymphocytes: analysis of BCL-1 rearrangements and expression of the cyclin D1 gene

The translocation t(11;14)(q13;q32) occurs in about 15% of patients with splenic lymphoma with villous lymphocytes (SLVL) or the closely related disorder lymphoplasmacytic lymphoma (LPL). To characterize the nature and frequency of rearrangements of the BCL-1 locus in SLVL/LPL and to document the effect of these genetic alterations on the expression of the cyclin D1 gene, we analyzed 22 cases of SLVL/LPL with defined cytogenetic abnormalities by both conventional electrophoresis (CE) and pulse-field gel electrophoresis (PFGE) and by Northern blotting. Four SLVL/LPL cases showed rearrangement of the BCL-1 locus. In two cases with t(11;14)(q13;q32), different breakpoints were identified; one mapped adjacent to the major translocation cluster (MTC) and the other within a 28-kb region telomeric of it. In a third case of SLVL with no cytogenetic abnormality of 11q13, a novel breakpoint approximately 100 kb centromeric of MTC was detected by PFGE. The fourth case, which had a normal karyotype, demonstrated rearrangement with a BCL-1 probe immediately telomeric of MTC. This case may have had a small deletion of 0.5 kb from within the BCL-1 locus. No rearrangement of the BCL-1 locus or within the cyclin D1 gene was detected by CE or PFGE in any of the remaining 18 SLVL/LPL samples. Northern blot analysis showed expression of a normal-sized cyclin D1 transcript in the two SLVL/LPL cases with t(11;14)(q13;q32). In cases that lacked a cytogenetically demonstrable t(11;14) translocation, no cyclin D1 transcript was detected. Analysis of the BCL-1 locus was also performed in three other cases of B-cell disorders with t(11;14)(q13;q32) detected cytogenetically. Two cases were analyzed by Southern blot and showed rearrangement of the BCL-1 locus. Expression of high-level normal-sized and/or truncated cyclin D1 transcript was also detected in these cases. These data show the importance of PFGE in the detection of rearrangements in the BCL-1 locus and show further the complexity of rearrangements in this locus.

Cytogenetic studies in splenic lymphoma with villous lymphocytes

We report the cytogenetic findings on 31 cases of splenic lymphoma with villous lymphocytes (SLVL). TPA stimulated cells from peripheral blood (28 cases), spleen (two cases) and lymph node (one case) with SLVL have been analysed. A clonal chromosome abnormality was found in 27/31 patients (87%); this was identified as a simple abnormality in 12 cases and a complex one in 15. Four recurring abnormalities were seen: t(11;14)(q13;q32) in five patients, deletions or translocations involving 7q in seven patients, iso 17q in four patients and translocations involving 2p11 in four patients. The high frequency of clonal chromosome abnormalities in SLVL contrasts with the usually benign clinical course of this disease. Abnormalities found frequently in patients with chronic lymphocytic leukaemia (CLL) such as trisomy 12 and deletions or translocations involving 13q14 were each seen in only one patient. No case had the t(14;18) characteristic of follicular lymphoma. Our findings demonstrate the high frequency of clonal and often complex chromosome abnormalities in SLVL. Although a unique chromosome rearrangement has not been identified, a pattern of four recurrent abnormalities has emerged. Our results suggest that SLVL is distinct on cytogenetic grounds from B-CLL and follicular lymphoma but shows similarity with mantle cell lymphoma, lymphoplasmacytic lymphoma and B-PLL.

Translocation t(11;14)(q13;q32) in chronic lymphoid disorders

The translocation t(11;14)(q13;q32) has been described in a spectrum of B-lymphoproliferative diseases and involves a putative oncogene, BCL1, which maps to chromosome band 11q13. Recent evidence indicates that this abnormality may delineate particular subtypes of lymphoma, such as intermediate lymphocytic and centrocytic lymphomas. Thus the possible significance of the t(11;14) within B-cell disorders should be reexamined in the light of a more objective approach to classifying these diseases by morphology, histology, and immunophenotype. We describe 16 patients with t(11;14)(q13;q32) from a series of 90 patients with chronic lymphoid disorders in whom clonal chromosome abnormalities were detected. All the cases were leukemic: prolymphocytic (B-PLL; 4/15 cases), chronic lymphocytic leukemia (CLL) with increase in prolymphocytes (2/9 cases), or non-Hodgkin lymphoma in leukemic phase, intermediate (3/4 cases), lymphoplasmacytic (2/2 cases), splenic lymphoma with villous lymphocytes (4/18 cases), and follicular (1 case). None of the CLL (25) or hairy cell leukemia cases (15) had t(11;14). Our findings showed that t(11;14) occurred in leukemias of mature B cells with lymphoplasmacytic features as judged by morphology and immunophenotype.

Clinical and laboratory features of 78 cases of T-prolymphocytic leukemia

We describe the clinical and laboratory findings of 78 adult patients with T-prolymphocytic leukemia (T-PLL) studied over the last 12 years. The main disease features were splenomegaly (73%), lymphadenopathy (53%), hepatomegaly (40%), skin lesions (27%), and a high leukocyte count (greater than 100 x 10(9)/L in 75%) with nucleolated prolymphocytes. A variant form with small, less typical cells was recognized in 19%. Membrane markers defined a postthymic phenotype TdT-, CD2+, CD3+, CD5+, CD7+; in 65%, the cells were CD4+ CD8-, in 21%, they coexpressed CD4 and CD8, and, in 13%, they were CD4- CD8+. Serology for human T-cell leukemia/lymphoma virus Type-I (HTLV-I) was negative in the 27 cases investigated. Cytogenetic analysis in 30 cases showed a consistent abnormality of chromosome 14, usually inv (14), with breakpoints at q11 and q32 in 76% of cases. Trisomy 8, including iso8q, was shown in 53%; t (11;14)(q13;q32) was documented in one case; and one had a normal karyotype. The clinical course was progressive with a median survival of 7.5 months. Thirty-one patients were treated with 2' deoxycoformycin and 15 responded (3 complete remissions and 12 partial remissions); the response rate (48%) increased to 58% in patients with a CD4+ CD8- phenotype. The median survival of responders was 16 months and of nonresponders 10 months; other treatments were less effective. T-PLL is a distinct clinico-pathologic entity with aggressive course and characteristic chromosome abnormalities. A subgroup of patients may benefit from deoxycoformycin.

Inversions and tandem translocations involving chromosome 14q11 and 14q32 in T-prolymphocytic leukemia and T-cell leukemias in patients with ataxia telangiectasia

Ataxia telangiectasia (AT) and T-prolymphocytic leukemia (T-PLL) have similar chromosome abnormalities. Cytogenetic findings reported in 5 patients with AT who developed T-cell leukemia revealed: inv(14)(q11q32) (1 case), tandem translocations of chromosome 14 with breakpoints at q11 and q32 (3 cases), and int. del(14)(q11q32) (1 case). Additional abnormalities were present in 4 patients of whom two had trisomy for 8q. Of 27 patients with T-PLL but without AT, investigated by us, 17 had inv(14)(q11q32) and 3 had tandem rearrangement of chromosome 14 with breaks at 14q11 and q32; 15 of them also had rearrangements resulting in trisomy 8q. Two of the leukemias supervening on AT had morphology and clinical course suggestive of T-PLL. Two other cases of AT studied by us developed typical T-PLL at a young age (18 and 39 years). T-cell clones carrying an inv(14), tandem t(14;14) and t(X;14) can be present in AT for long periods of time without evolving into leukemia. In T-PLL, inv(14) and t(14;14) always occurs with other chromosome abnormalities. We suggest that these additional chromosome abnormalities may be required for the leukemic transformation of AT. This is supported by one of the two AT cases studied by us in which a long-standing t(X;14) clone evolved with the formation of t(1;14)(p21;q11), t(8;22)(q24;q11) at the time of the development of T-PLL.

Leukaemia as a manifestation of large cell lymphoma

A leukaemic phase is uncommon in large cell lymphoma, particularly at presentation of the disease, and very few cases have been reported since immunological markers became available. We have studied 24 cases presenting over a period of 15 years. 16 were B-lineage and eight T-lineage. In five patients the large cell lymphoma represented a transformation of a preceding low grade, small cell lymphoproliferative disease. Three other patients with T-lineage large cell lymphoma presented with skin infiltration (two cases) or lymphoma-associated nephrotic syndrome (one case) 3-9 months before leukaemia occurred. The other 16 patients (12 B-lineage and four T-lineage) presented with de novo large cell leukaemia/lymphoma. With the exception of skin infiltration, clinical features did not differ between T and B-lineage cases. Prognosis was generally poor although a minority of patients lived 1-2 years. Median survival was 7 months. In the B-cell lymphomas immunological markers were those expected but among the T-cell cases there were many unusual immunophenotypes with frequent failure to express markers which are usually positive in peripheral T cells. Without the availability of immunological markers diagnosis would have been difficult, with acute myeloid leukaemia being the most important differential diagnosis. T-lineage and B-lineage cases could not be distinguished on cytological features. In the majority of cases the cells were very pleomorphic with nuclear lobulation, prominent nucleoli and marked cytoplasmic basophilia being commonly observed. Marked nuclear lobulation was not confined to T-lineage cases but was seen also in seven of 12 cases of de novo B-lineage leukaemia/lymphoma; it was readily apparent in histological sections and on ultrastructural examination.

Translocations t(14;18) and t(8;14) with rearranged bcl-2 and c-myc in a case presenting as B-ALL (L3)

Follicular lymphoma is a low grade malignancy characterized by the translocation t(14;18), which involves the putative oncogene bcl-2. We describe a 73-year-old patient presenting with Burkitt acute lymphoblastic leukemia (B-ALL) L3 (Burkitt type), whose cells had the following immunophenotype: CD19+, CD22+, HLA-DR+, CD10+, TdT-, Cyt IgM-, CD34-. Analysis of 25 peripheral blood metaphases showed the presence of t(14;18) (q32;q21), and t(8;14) (q24;q32) in 24 cells and t(14;18) only in one cell, suggesting that the latter translocation came first during clonal evolution. Both bcl-2 and c-myc were rearranged in addition to the immunoglobulin heavy and light chain genes. The presence of small lymphoid cells in paratrabecular areas on the bone marrow biopsy, together with evidence of cytogenetic clonal evolution, was indicative of a transformation from a low grade follicular lymphoma to a more aggressive Burkitt type malignancy.

The establishment of cell lines from chronic B cell leukaemias: evidence of leukaemic origin by karyotypic abnormalities and Ig gene rearrangement

We have studied the capacity of peripheral blood cells from 26 chronic B cell leukaemias to proliferate continuously in culture; 72 attempts to establish cell lines were made. The cells were treated in vitro with or without stimulating agents: Epstein-Barr virus (EBV) and/or phorbol-ester (TPA) were the most frequently used. Fourteen cell lines of continuous growth were established from cells from 11 patients, but only four of these were proven to be derived from the original leukaemic cells. Only in the latter four lines were the karyotypic abnormalities and the patterns of immunoglobulin (Ig)-gene rearrangements identical to those found in the patients' leukaemic cells. On the other 10 lines, five had both kappa- and lambda-producing cells, and the remaining five, despite showing light-chain restriction, were proved to be non-leukaemic clones by comparing the Ig-gene rearrangement patterns before and after culture. Three of the four leukaemic cell lines (JVM-2, JVM-3 and JVM-13) were induced by EBV + TPA and derived from prolymphocytic leukaemia (PLL) cases; the fourth (JVM-14) originated from a case of chronic lymphocytic leukaemia (CLL) with increased percentage of prolymphocytes whose cells were stimulated in vitro with EBV. The immunophenotype of the three PLL lines is more mature than that of the original prolymphocytes, as shown by a reduction in surface-Ig and FMC7 expression, enhancement of cytoplasmic-Ig and increase in CD38- and transferrin receptor-positive cells. The cells from line JVM-14 retained the CD5-antigen, a marker of CLL. This study suggests that PLL and some CLL clones are arrested at a stage of maturation ideally suited to be triggered to continuous proliferation in culture. The presence of consistent chromosomal abnormalities in PLL may offer an alternative explanation for the greater proliferative potential of these cells in vitro.

A t(8;14)(q24;q32) in a T-lymphoma/leukemia of CD8+ large granular lymphocytes

Chromosome studies in a case of T cell lymphoma/leukemia, in which a high proportion of the dividing cells had a t(8;14)(q24;q32) similar to that seen in Burkitt's lymphoma, are described. The tumor cells had a mature T cell phenotype (TdT-,CD3+,CD8+,CD4-) and were morphologically large granular lymphocytes and immunoblasts, both cell types with similar lysosomal granules in the cytoplasm. The immunoglobulin heavy chain gene and the T cell receptor beta chain gene were not rearranged, while the T cell receptor gamma chain gene was polyclonally rearranged. Mitoses were obtained only from spontaneously dividing cells in the absence of mitogens; 49 of the 50 metaphases analyzed were chromosomally abnormal and had a t(1;22)(q12;q13) and dup(1)(q31q32) in all of them; 48 metaphases had in addition a t(8;14)(q24;q32) which presumably arose during clonal evolution. The latter may be associated with the aggressive behavior of this T cell disorder by comparison with other proliferations of large granular lymphocytes. Although abnormalities involving 14q32 are characteristic of B cell disorders, they have also been described in T cell malignancies, suggesting that genes transcribed in T cells and/or oncogenic sequences significant in T cell neoplasia are present in 14q32.

Cytogenetic studies on prolymphocytic leukemia. II. T cell prolymphocytic leukemia

We report chromosome abnormalities in 15 cases of T cell prolymphocytic leukemia (T-PLL). All cases were characterized by clinical, morphological, and membrane marker analysis. The most frequent abnormality was an inv(14)(q11q32) observed in nine cases. The T cell receptor (TCR) alpha chain gene is localized to 14q11 and the immunoglobulin heavy-chain gene to region 14q32. Four cases also had translocations involving 14q11. Trisomy or multisomy for 8q resulting from an i(8q) or from rearrangements with 8p12 as the breakpoint was observed in nine cases, and a deletion of 6q was found in four cases. Trisomy or partial trisomy for 7q was observed in four cases, of which two had abnormalities of band 7q35 to which the TCR beta chain gene is mapped. The expression of Tac antigen, investigated in 27 cases of human T cell leukemia virus I-negative chronic T cell leukemia, which included the 15 cases of T-PLL, showed a good correlation with abnormalities of 7q35. Our studies on chronic T leukemias suggest that inv(14)(q11q32) and trisomy for 8q are abnormalities characteristic of T-PLL.

'Pseudo-lymphoid' leukaemia with unusual features: ultrastructural, immunological, cytogenetic and molecular studies

An unusual case of 'pseudo-lymphoid' leukaemia is described. The leukaemic cells resembled small, mature lymphocytes but lacked B- and T-cell membrane markers as well as immunoglobulin (Ig) and T-cell receptor gene rearrangements. They showed, instead, features of early myeloid cells since they expressed 2 myeloid antigens, CDW13 and My9, and displayed peroxidase activity demonstrable by electron microscopy (EM) on unfixed cells. Cytogenetic studies showed monosomy 5, t(4;17) (p12;p11), t(2;3)(p23;q14) and an abnormal chromosome 12. Abnormalities of chromosomes 4 and 5 have been previously associated with 'pseudo-lymphoid' leukaemias. This case illustrates the value of sensitive methods for the characterization of blast cells and for the precise diagnosis of leukaemias with apparent 'lymphoid' morphology.

Variant translocation t(8;22) and abnormalities of chromosome 15(q22) and 17(q12-21) in a Burkitt's lymphoma/leukaemia with disseminated intravascular coagulation

Severe disseminated intravascular coagulation was observed in a patient with Burkitt's lymphoma/leukaemia. Immunological studies on leukaemic blasts from relapsed bone marrow revealed a B-cell phenotype (B4+, B1+, HLA-Dr+, J5+) with membrane bound IgM lambda. Cytogenetic investigation revealed a variant Burkitt's translocation t(8;22)(q24;q11) involving the lambda light chain gene region and abnormalities of chromosomes 15 and 17 with breakpoints at q22 and q12 respectively, similar to those observed in the t(15;17) in acute promyelocytic leukaemia. Transmission electron microscopy of the leukaemic blasts showed crystalline cytoplasmic inclusions which may have had a role in precipitating the disseminated intravascular coagulation.

Two new cell lines from B-prolymphocytic leukaemia: characterization by morphology, immunological markers, karyotype and Ig gene rearrangement

Leukaemic cells from 2 patients with B-prolymphocytic leukaemia were immortalized in vitro by means of Epstein-Barr virus and phorbol-ester TPA. The resulting cell lines, named JVM-2 and JVM-3, have been growing continuously in liquid culture for more than one year. JVM-2 is characterized cytogenetically by t(11;14)(q13; q32), and JVM-3 by trisomy 12. The immunoglobulin (Ig) heavy- and light-chain genes showed the same pattern of rearrangement in both lines as in the original prolymphocytes from each case. The cells from these lines showed a spectrum of morphological and immunological features corresponding to different stages of B-cell maturation. The expression of Ig, IgM-lambda in JVM-2 and IgMD-K in JVM-3, changed from a predominantly membrane pattern in the original cells to a cytoplasmic one in the cell lines. By comparison with their original progenitors, the cells from both lines showed reduced reactivity with the monoclonal antibody (MAb) FMC7, and increased expression of the antigens recognized by the MAbs OKT10, alpha-Tac, FMC53 and Ki-I. The availability of cell lines from this rare type of lymphoid leukaemia offers a potential tool for the study of molecular events associated with the expression of Ig and other antigens by neoplastic cells.