Identification of a unique erythroleukemia-associated retroviral gp70 expressed during early stages of normal erythroid differentiation.

Abstract

Late in the course of Friend virus (FV)-induced erythroleukemia, leukemic spleen cells express a cell surface retroviral gp70 envelope protein not detected during the early proliferative phase of the disease. Characterization of this gp70 revealed it was unrelated to the input Friend murine leukemia virus (F-MuLV), but antigenically similar to a unique subset of endogenous xenotropic viruses. This gp70 was expressed by murine erythroleukemia cell lines but has not been identified on cell lines of other lineages. A monoclonal antibody (18-6) specifically reactive with this polypeptide was used to examine hematopoietic organs of normal uninoculated mice. This antibody detected a gp70 expressed by a majority of erythroid cells in fetal liver and by a small but significant percentage of normal adult spleen and bone marrow cells. Increased erythropoietic activity induced by treatment of adult mice with phenylhydrazine ( PHZ ) resulted in a seven- to eightfold increase in the frequency of spleen and bone marrow cells expressing this gp70. Peptide map analysis indicated that the 18-6 reactive gp70 expressed by Friend erythroleukemia cells and by cells from normal fetal liver were structurally identical. These results suggested that this unique gp70 was an erythroid-specific differentiation antigen.

The monoclonal antibody TER‐119 recognizes a molecule associated with glycophorin A and specifically marks the late stages of murine erythroid lineage

“…In mice, several mAbs that react with the erythroid lineage have been reported. They are directed either to a gp70 retroviral antigen (Britt et al , 1984) or to an idiotypic determinant on the viral receptors (Ardman et al , 1987). Expression of these determinants appears to be limited only to a certain stage of erythroid cells or to erythroleukaemia cells.…”

“…Although the expression of glycophorin molecules has been well studied in human erythroid cells, little is known about glycophorin expression in the mouse. There are several mAbs that are shown to be reactive with murine erythroid cells, but none of them have been demonstrated as specific markers for erythroid lineage (Britt et al, 1984;Ardman et al, 1987;Bacon & Sytkowski, 1987). During the preparation of mAbs to mouse fetal antigens, we previously established a hybridoma clone TER-119 which produces a rat mAb selectively reactive with both fetal and adult erythroid cells (Ikuta et al, 1990).…”

Endogenous Retroviral Envelope Antigens Recognized by B Lymphocytes during Graft-Versus-Host Reaction.

“…Cell lines derived from the leukemic spleens of these mice proliferate autonomously in vitro. Britt et al (1984) observed that during the early proliferative phase of Friend disease, spleen cells expressed high levels of envelope glycoprotein of the F-MuLV helper virus, but during the late leukemic phase, there was a loss of this protein, associated with the simultaneous appearance of a unique xenotropic gp7O reactive with one of the GVHR antibodies 18-6. The 18-6 antibody detects a gp7O epitope which defines a subclass of xenotropic viruses (Portis et al 1982).…”

Antigenic Subclasses of Polytropic Murine Leukemia Virus (MLV) Isolates Reflect Three Distinct Groups of Endogenous Polytropic MLV-Related Sequences in NFS/N Mice

“…These markers can be detected in samples by a variety of techniques (2,3,34) and should greatly facilitate the identification of proviruses that participate in recombination. Furthermore, endogenous proviral genes are expressed in a tightly controlled fashion at various times and in various tissues of mice (5,30,31,36,54). The expression of these sequences may have a physiological role and certainly has physiological consequences in some mouse strains, such as those that exhibit a high incidence of leukemia.…”