Evidence for chemical differences in HLA-DR molecules on autologous acute
lymphoblastic leukemia and B-lymphoblastoid cell lines [published erratum
appears in Blood 1987 Apr;69(4):1272]
L Graf and JM Pesando
HLA-DR molecules on autologous acute lymphoblastic leukemia (ALL) and B-
lymphoblastoid cell lines from two individuals were compared by immune
precipitation and gel electrophoresis. Cells were surface labeled with 125I
and proteins immunoprecipitated with specific monoclonal antibodies (MoAb).
Two electrophoretically distinct bands were found in the HLA-DR beta chain
region on both ALL cell lines in contrast to only one on each of the
autologous B-lymphoblastoid cell lines. Differences in the electrophoretic
mobility of the alpha chains were also observed with ALL and
B-lymphoblastoid cell lines from one individual. Preclearing of
radiolabeled cell lysates with MoAb specific for HLA-DQ and -DP molecules
demonstrated that the complexity of the HLA-DR pattern is not the result of
antibody cross-reactivity with alpha and beta chains from other class II
products. Immunoprecipitation experiments indicated that two beta chain
bands are observed with each of the parental HLA-DR molecules on the ALL
but not the B- lymphoblastoid cell line from an HLA-DR3,7-positive
individual. We conclude that the HLA-DR molecules expressed on ALL and B-
lymphoblastoid cell lines from the same individual can differ chemically.
Neuraminidase treatment reduced these electrophoretic differences,
indicating that these molecules differ in their sialic acid content. Since
small changes in class II molecules can profoundly alter cellular
interactions, the functional significance of these differences requires
further investigation.
Volume 69,
Issue 1,
pp. 7-11,
01/01/1987
Copyright © 1987 by The American Society of Hematology
