A comparative analysis of cytoplasmic mu (C mu) expression in acute lymphoblastic leukemia by molecular and immunologic techniques. Identification of leukemia cases expressing C mu mRNA transcripts in the absence of detectable C mu proteins.
Among acute lymphoblastic leukemias derived from the B-cell lineage, the subset of cases expressing cytoplasmic mu heavy chain proteins (C mu) in the absence of surface immunoglobulin has been designated pre-B-cell acute lymphoblastic leukemia. This group, traditionally identified using immunologic smear techniques, has been associated with a poor prognosis in some series. In a comparative study, 25 cases of B-lineage acute lymphoblastic leukemia were analyzed for C mu expression using molecular and immunologic techniques. RNA derived from cryopreserved blast cells was hybridized in both Northern and slot-blot analyses using a probe (pBZ311) containing four exons of the human immunoglobulin heavy chain mu constant region gene. Expression of C mu proteins was assessed simultaneously by slide immunofluorescence and flow cytometric techniques in all samples. These studies were correlated with immunoglobulin heavy and light chain gene rearrangements, cell-surface immunophenotype, cytogenetics, and other clinicopathologic features. C mu mRNA transcripts were detected in 14 of 25 cases, whereas C mu proteins were detected in only 9 of these cases using flow cytometric techniques. Only four of these nine cases were positive by slide immunofluorescence techniques. These studies imply that molecular and flow cytometric techniques may be a more sensitive means to assess C mu expression. The identification of five cases that expressed C mu mRNA transcripts in the absence of detectable C mu proteins also suggests that molecular techniques may be valuable in identifying a unique subgroup of pre-B-cell acute lymphoblastic leukemia cases that contain C mu mRNA transcripts, but lack C mu proteins.
Little
J V
JV
Department of Pathology, University of New Mexico School of Medicine, Albuquerque.
Foucar
K
K
Duncan
M H
MH
Crago
S S
SS
McConnell
T S
TS
Griffith
B
B
Chen
I M
IM
Vogler
L B
LB
Willman
C L
CL
D000293:Adolescent; D015152:Blotting, Northern; D015139:Blotting, Southern; D002648:Child; D002675:Child, Preschool; D003593:Cytoplasm / Q000737:chemistry*; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000276:immunology*; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000032:analysis* / Q000235:genetics; D016130:Immunophenotyping; D007223:Infant; D007621:Karyotyping; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis*; D012334:RNA, Neoplasm / Q000032:analysis*
D004273:DNA, Neoplasm; D007148:Immunoglobulin mu-Chains; D012333:RNA, Messenger; D012334:RNA, Neoplasm