Lack of allelic exclusion and isotype switching in B cell chronic lymphocytic leukemia.
Two rearranged bands of the IgH gene were detected in a case with B cell chronic lymphocytic leukemia (B-CLL). The expressed VH gene was only VH1 with no somatic mutations in IgM and IgD. The expressions of C mu, C delta, and C gamma were detected by reverse transcription of RNA followed by the polymerase chain reaction (RT-PCR). Sequence analysis of the CDR3 regions of each PCR reaction product showed that the sequence of one rearranged allele was identical to those of the expressed VH1 gene, C mu and C delta, and the sequence of another rearranged allele was identical to that of C gamma. However, none of the expressed VH genes was detected in IgG. These findings suggest that this is a case of B-CLL lacking allelic exclusion and undergoing a class switch of one allele with the incomplete expression of the VH gene.
Katayama
Y
Y
Department of Hematology and Oncology, Division of Clinical Research, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku Hiroshima 734-8553 Japan.
Sakai
A
A
Katsutani
S
S
Takimoto
Y
Y
Kimura
A
A
D000368:Aged; D000483:Alleles; D001483:Base Sequence; D022801:Complementarity Determining Regions; D020732:Cytogenetic Analysis; D005260:Female; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain / Q000235:genetics; D006801:Humans; D017578:Immunoglobulin Class Switching; D016130:Immunophenotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction
D022801:Complementarity Determining Regions