Bone marrow stroma-dependent modulation of CD45R isoform expression on Abelson virus transformed pre-B cells.
Immunol Invest
; 24(3): 509-22, 1995 Mar.
Article
em En
| MEDLINE
| ID: mdl-7540594
ABSTRACT
The CD45 glycoprotein family exhibits cell-lineage-associated structural heterogeneity which is due, in part, to alternative pre-mRNA splicing. The Abelson murine leukemia (A-MuLV) preferentially transforms immature B cells that express a B-cell-specific high molecular weight CD45 isoform, called B220. However, we observed that A-MuLV-transformed cell lines are often B220- while maintaining high levels of "pan" CD45 expression. In vitro transformation of murine bone marrow revealed that the stromal microenvironment over which A-MuLV-transformed lymphoblasts are grown affected the B220 phenotype of the pre-B cells. Over a period of a few weeks, B220+ populations grown over a clonal stromal cell line gradually became B220-. However, the transition from a B220+ to B220- phenotype was dependent on the lot of fetal calf serum used. In contrast, cells grown over a heterogeneous bone marrow stroma maintained B220+ expression for long periods of time. The appearance of B220- cells in clonal B220+ populations indicated that the change in phenotype resulted in part from modulation of B220 expression. B220- B-cell lines did not express the high molecular weight CD45 RNA species indicating that the B220- phenotype was due to alternative pre-mRNA splicing. Finally, the shift from B220+ to B220- was not accompanied by changes in the stage of development of the cultures. These observations demonstrate that expression of B220 is not required for the continued proliferation of Abelson-transformed pre-B cells and is regulated by unknown environmental factors.
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Base de dados:
MEDLINE
Assunto principal:
Células da Medula Óssea
/
Linfócitos B
/
Modulação Antigênica
/
Antígenos Comuns de Leucócito
Idioma:
En
Ano de publicação:
1995
Tipo de documento:
Article