FISH and related techniques in the diagnosis of lymphoma.

Many malignant lymphomas are characterized by recurrent genetic abnormalities. These include numerical abnormalities, deletions and reciprocal translocations. In this chapter, we have focused on the detection of chromosomal translocations in B cell lymphomas and discussed some trisomies in lymphomas and CLL. FISH is a well developed molecular method by which it is possible to detect numerical and structural chromosomal abnormalities. We addressed various aspects of metaphase, and especially interphase, FISH and also described the recently developed DNA fibre FISH technology. Using this method, it is possible simultaneously to detect and map chromosomal breakpoints. FISH is also compared with more conventional detection methods such as banding analysis, Southern blot analysis and PCR for the translocations t(8;14) and variant translocations in Burkitt's lymphoma, t(14;18) in follicular lymphoma and t(11;14) in MCL. Other breakpoints in B cell lymphoma are also discussed. It might be concluded that the rapid development in interphase and DNA fibre FISH will provide us with quick, easy and cheap tools to identify specific chromosomal translocations and other genomic abnormalities in human tumours.

Decreased expression of cellular markers in Epstein-Barr virus-positive Hodgkin's disease.

Epstein-Barr virus (EBV) has been demonstrated in the Reed-Sternberg cells and their mononuclear variants (Hodgkin cells; H-RS cells) in a substantial number of Hodgkin's disease (HD) cases. Moreover, EBV can modulate both in vivo and in vitro the expression of several cellular genes, including lymphoid differentiation markers. Therefore we investigated, in 64 cases of HD, the relationship between the presence of EBV and the expression of lymphoid (CD45RB), T- (CD3, CD45RO), B- (CD20, MB2 antigen, CDw75), and myeloid-cell lineage markers (CD15), and of activation markers (CD30, EMA, and the 115D8 antigen) on the H-RS cells. EBV-positive cases, as demonstrated by the presence of EBER-1 and -2 RNA and LMP-1 protein expression, showed a significant reduction in the expression on H-RS cells of T-cell lineage (CD3, P < 0.02), B-cell lineage (CD20; P < 0.005), and activation markers (EMA; P < 0.002 and the 115D8 antigen; P < 0.001) as compared with EBV-negative cases. No differences were found in the expression of CD15, CD30, CD45RO, CD45RB, CDw75, or the MB2 antigen on H-RS cells in EBV-positive and EBV-negative HD cases. Interestingly, in 11 cases of EBV-negative HD, B- as well as T-cell lineage markers could be found on some H-RS cells. These data suggest that EBV in H-RS cells is able to down-regulate the expression of T- (CD3) and B- (CD20) cell lineage markers and lymphoid activation markers (EMA and the 115D8 antigen).(ABSTRACT TRUNCATED AT 250 WORDS)