MICROSATELLITE INSTABILITY IS RARE IN B-CELL NON-HODGKINS-LYMPHOMAS

Microsatellite instability (MSI), a symptom of defect in DNA mismatch repair function, represents a type of genomic instability frequently d etected in many types of cancers. However, the involvement of MSI in n on-Hodgkin's lymphomas (NHL) has not been conclusively investigated. I n this study, we have tested the presence of MSI in 69 cases of B-cell NHL (B-NHL) representative of the various histologic categories of th e disease and including 17 cases of acquired immunodeficiency syndrome (AIDS)-related B-NHL (AIDS-NHL). In addition, for selected B-NHL case s, consecutive samples obtained before and after clinical progression (with and without concomitant histologic transformation) were also inv estigated. Five distinct microsatellite repeats (2 dinucteotide, 2 tri nucleotide, and 1 tetranucleotide repeats) were analyzed by polymerase chain reaction in all cases. MSI, defined by the presence of microsat ellite alterations in two or more of the five microsatellite loci test ed, was not found in NHL. In contrast to a previous study reporting th e frequent association between MSI and AIDS-NHL, we found this abnorma lity in only 1 of 17 cases of AIDS-NHL representative of the major sub types. Overall, these data indicate that defects in DNA mismatch repai r do not contribute significantly to the molecular pathogenesis of B-N HL. (C) 1997 by The American Society of Hematology.