Immunogenotypes of lymphoid malignancies; the rearrangement of T cell receptor beta chain gene can occur before the gamma chain gene rearrangement.

Immunoglobulin (Ig) and T cell receptor (TcR) gene rearrangements were analyzed in 101 cases of lymphoid malignancies in association with a surface phenotype study. In leukemias/lymphomas with mature phenotype, there is a good correlation between phenotypes and genotypes. However, in leukemias/lymphomas with immature phenotype, we found many discordances between phenotypes and genotypes, suggesting the stochastic nature of hematopoietic cell differentiation at the early stage. As for TcR beta and gamma chains, the rearrangement of gamma chain gene is considered to occur slightly prior to that of beta chain gene. However, we observed a mature T cell malignancy, adult T-cell leukemia, with rearranged beta chain gene and germ line gamma chain gene, showing the possible existence of another pathway of T cell differentiation.