Concomitant rearrangements of T-cell beta- and gamma-chain genes in childhood T-lineage leukemia/lymphoma

CD3-negative lymphoproliferative disease of granular lymphocytes containing Epstein-Barr viral DNA

Lymphoproliferative disease of granular lymphocytes (LDGL) is a heterogeneous disorder and the pathogenesis is likely to be complex. Some patients with chronic active EBV (CAEBV) infection also have LDGL. To investigate the relationship between EBV infection and the pathogenesis of LDGL, we conducted a survey for EBV DNA sequences by Southern blot analysis of DNA obtained from the peripheral blood of seven patients with LDGL, including one with CAEBV infection. Interestingly, EBV DNA was detected in the sample from the patient with CAEBV infection, and in the samples from four other patients with CD3-LDGL. Moreover, a single band for the joined termini of the EBV genome was demonstrated in two samples, suggesting a clonal disorder of those LDGL. These findings strongly suggest that EBV may play a pathogenic role in some cases of LDGL.

Poor prognosis of mediastinal non-Hodgkin's lymphoma with an immature phenotype of CD2+, CD7 (or CD5)+, CD3-, CD4-, and CD8-

Nine children with mediastinal non-Hodgkin's lymphoma (NHL) were treated according to our new regimen which is characterized by intensified therapy with high-dose cytosine arabinoside (HDCA). After induction therapy with a combination of five drugs, such as vincristine, doxorubicin, cyclophosphamide, 1-asparaginase, and prednisolone, intermediate dosages of methotrexate (MTX) (1 g/m2) and HDCA (1.5 g/m2 x 12 doses) were administered. All but one patient (88.9%) achieved complete remission and then received this intensified therapy. With a median follow-up period of 25.5 months, five patients are still in complete remission, but three patients have relapsed. From the phenotypic point of view, these relapsed patients showed only very immature T-cell differentiation antigens such as CD2 and CD7 (or CD5). These results suggest that HDCA as intensified therapy for children with mediastinal NHL seems to be effective. However, for patients with an immature phenotype of T-lineage cells, more sophisticated regimens should be prepared.

T-cell receptor beta-chain gene expression in B-lineage acute lymphoblastic leukemia

The T-cell receptor beta-chain (T beta) gene expression was examined in 16 children with B-lineage acute lymphoblastic leukemia (ALL), including eight patients with rearrangement of the T beta gene as well as immunoglobulin (Ig) heavy chain gene rearrangement. In contrast to the 1.3 kb full-length transcripts of the T beta observed in T-lineage leukemia and lymphoma cells, no transcript of the T beta gene was detected in 10 patients, including four with T beta gene rearrangement. Low levels of T beta transcripts were found in three patients with T beta gene rearrangement and two patients without T beta gene rearrangement, but those transcripts were truncated. In contrast to those findings, a single patient with T beta gene rearrangement showed abundant 1.3 kb T beta transcripts. These data indicate that T beta gene expression is not restricted to T-lineage cells and demonstrate the heterogeneity of B-lineage ALL at the expression level of the T beta gene. Our findings also suggest that T beta gene expression is not always accompanied with T beta gene rearrangement.