A human uveal melanoma cell line (92-1) was established from a primary uveal melanoma, and has now been maintained in culture for over 2 1/2 years. Light microscopy of the cultured cells demonstrated extremely pleiomorphic cells with large prominent nucleoli. Cell proliferation was determined with a non-radioactive propidium-iodide assay and indicated an in vitro doubling time of approximately 58 hr. Furthermore, the cell line was characterized by cytogenetic analysis, electron microscopy, immunocytochemistry and Northern blotting for HLA and c-myc-mRNA analysis. Cytogenetic analysis revealed numerical abnormalities of chromosome 8 and structural abnormalities of chromosome 6. By electron microscopy, different stages of melanosome development were observed. Immunocytochemical analysis demonstrated expression of the melanoma-associated antigen gp 100. Expression analysis of HLA antigens revealed a very low level of, in particular, the HLA-B locus products, which could be induced by interferon-alpha or -gamma treatment. Likewise, Northern-blot experiments revealed decreased levels of HLA-B mRNA as compared with HLA-A. In addition, high levels of c-myc expression were observed. The phenotypic characteristics of the cultured cells indicate that we have established an uveal melanoma cell line. This now well-characterized uveal melanoma cell line can be used in future studies.

Double fluorescence in situ hybridization was used to detect Philadelphia (Ph) chromosomes in interphase nuclei and metaphases of patients with chronic myeloid leukemia. Application of cosmid probes for 3’ ABL and 5’ BCR sequences gave better results than libraries for chromosomes 9 and 22. The present approach may provide an alternative method for monitoring minimal residual disease in Ph⁺ CML patients.

Myelodysplasia (MDS) and leukaemia following acquired aplastic anaemia has been reported as a rare event occurring in about 5% of patients. Improved results in survival of patients with severe aplastic anaemia (SAA) and subsequent prolonged follow-up created the possibility of evaluating the occurrence of MDS and leukaemia in 38 adult patients with acquired SAA surviving two or more years without bone marrow transplantation. Five patients, age 22, 35, 47, 56, 72 years, two females, three males, all with idiopathic SAA and normal cytogenetic analysis developed a refractory anaemia (RA) 7, 30, 48, 56, 142 months after diagnosis of SAA. In 3/5 RA evolved into an acute myeloid leukaemia (AML) either via a chronic myelomonocytic leukaemia (CMML) (2/3) or via RA with excess of blasts (RAEB) (1/3). Three patients revealed a monosomy 7 during MDS and/or leukaemic phase. One patient died during RA phase without cytogenetic abnormalities. A pattern of evolution could be identified in these patients revealing well-documented SAA - improvement of bone marrow haematopoiesis - dyshaematopoietic features of one or more cell lines with predominance of dyserythropoiesis - RA - RAEB or CMML - AML. These five patients represent more than 10% of all patients surviving at least 2 years. This implies that the risk of developing MDS and leukaemia in SAA patients surviving with autologous marrow, might increase with longer follow-up.

Infant acute lymphoblastic leukemia (ALL) with MLL gene rearrangements is characterized by a proB phenotype and a poor clinical outcome. We analyzed an infant proB ALL with t(2;11)(p15;p14) and an MLL rearrangement on Southern blot analysis. Rapid amplification of cDNA ends-polymerase chain reaction (PCR) and reverse transcriptase-PCR identified the LAF4 gene mapped on chromosome region 2q11.2-q12 as a fusion partner of the MLL gene. The LAF4 gene was identified previously by its high sequence homology to the AF4 protein and encodes a protein of 1,227 amino acids. The t(4;11)(q21;q23), creating the MLL-AF4 chimeric transcripts, is the predominant 11q23 chromosome translocation in infant ALL and is associated with an extremely poor prognosis. Our findings further suggest that fusion of MLL to one of the AF4 family members (AF4/LAF4/AF5Q31) might determine a proB-cell phenotype in infant leukemia.