REARRANGEMENTS OF IMMUNOGLOBULIN AND T-CELL RECEPTOR GENES IN CANINE LYMPHOMA LEUKEMIA-CELLS

Tumor cells from 15 canine lymphoma/leukemia cases were examined for g enetic rearrangements of immunoglobulin and T-cell receptor (TCR) gene s in parallel with cell surface antigens. Ten of these 15 cases showed rearrangements of the immunoglobulin heavy chain (IgH) gene, while 4 cases displayed TCRbeta-chain gene rearrangements on Southern blot ana lysis. All the cases with IgH gene rearrangements had multicentric for m lymphoma, and 6 of the 10 cases were cell surface immunoglobulin-pos itive. On the other hand, the cases with TCR gene rearrangements inclu ded atypical lymphoma/leukemia cases, and 3 of the 4 cases were Thy-1 antigen-positive. Although the tumor cell lineage of a considerable nu mber of lymphoma/leukemia cases could not be determined by phenotypic analysis, examination of the IgH and TCR gene rearrangements disclosed the lineages of 14 of 15 cases. Genetic analysis demonstrated that th e tumor cells in most canine multicentric lymphomas were formed by clo nal expansion of B-lymphocyte. These findings show that studies on the rearrangements of immunoglobulin and TCR genes are very useful for un derstanding the cellular origin, clonality and hierarchy of canine lym phoma/leukemia cells.