Rearrangement and diversification of immunoglobulin light-chain genes in lymphoid cells transformed by reticuloendotheliosis virus.

Abstract

Avian lymphoid cells transformed by reticuloendotheliosis virus (REV-T) serve as a model to analyze the mechanism by which B-cell differentiation and antibody diversification occur in birds. Immunoglobulin light-chain gene rearrangements, diversification, and expression were analyzed in 72 independently derived REV-T-transformed cell lines. Lymphoid cells transformed as the result of expression of the v-rel oncogene were divided into two distinct groups based on light-chain gene rearrangements. The status of the light-chain gene loci in these REV-T-transformed cell lines was determined in part by the ages of the chickens whose spleen cells were transformed. In embryonic spleen cell lines transformed by the v-rel oncogene, rearrangements were not detected, even after prolonged culture in vitro, indicating that these cells are arrested in B-cell differentiation. REV-T transformants derived from spleens obtained from chickens 2 weeks old or older, however, had at least one light-chain allele rearranged. All of the cell lines analyzed which exhibited rearranged light-chain genes contained light-chain transcripts, and most of the REV-T-transformed cells which displayed light-chain rearrangements expressed immunoglobulin protein. REV-T, therefore, transforms B-lymphoid cells at phenotypically different stages of development. Many REV-T-transformed cells undergo immunoglobulin chain gene rearrangements during prolonged propagation in vitro. Most of the cell lines which rearrange their light-chain alleles also undergo diversification during cultivation in vitro. Light-chain diversification occurs during or after the rearrangement event.

Stochastic rearrangement of immunoglobulin variable-region genes in chicken B-cell development.

“…In contrast to other reports of REV-T-transformed chicken B-lineage cells (27)(28)(29), we have found no evidence for gross chromosomal abnormalities or deletions involving the Ig Hor L-chain locus among the clones we have isolated. This may reflect the helper virus used for producing REV-T, since the helper virus used elsewhere (REV-A, refs.…”

Ongoing diversification of the rearranged immunoglobulin light-chain gene in a bursal lymphoma cell line.

“…Under these conditions, over prolonged culture in vitro no evidence of a significant rate of sequence modification within the rearranged lgL gene has been obtained by either restriction site analysis or by sequencing (C. Postema and C. B. Thompson, unpublished data). Although a recent report has been published suggesting that some v-rel cell lines may retain the ability to diversify immunoglobulin genes (30), the frequency at which these events were reported to occur was extremely low. We have been unable to duplicate these results in our own laboratory.…”

Multiple mutations contribute to the oncogenicity of the retroviral oncoprotein v-Rel

“…Moreover, vRel-transformed cell lines, established by in vitro infection of chicken spleen cells and which do not shed helper virus, can induce fatal tumors with as few as 100 cells when injected into histocompatible chickens (Lewis et al, 1981). Cells transformed in vitro by v-Rel have been reported to have characteristics of immature pre-B/pre-T cells (Beug et al, 1981;Chen et al, 1988;Morrison et al, 1991;Zhang et al, 1989), abnormal B cells (Chen et al, 1988), immature and mature B cells (Benatar et al, 1991(Benatar et al, , 1992Boehmelt et al, 1995;Keller et al, 1979;Lewis et al, 1981;Sasaki and Koyama, 1989;Shibuya et al, 1982;Zhang et al, 1991), T cells (Barth et al, 1990;Marmor et al, 1993;Schat et al, 1992), myeloid cells (Barth et al, 1990;Morrison et al, 1991), erythroid cells (Morrison et al, 1991), and pre-dendritic cells (Boehmelt et al, 1995).…”

“…Third, in some experiments, slightly di erent variants of v-rel may have been used; v-Rel proteins that di er only at aa 40 preferentially transform B cells (Romero and Humphries, 1995). Fourth, the age of the chicken from which bone marrow or spleen cells were taken can a ect the transformed cell types seen (Zhang et al, 1989(Zhang et al, , 1991. Fifth, v-Rel-transformed cells can undergo continued di erentiation after establishment in vitro (Zhang et al, 1989).…”

“…Fourth, the age of the chicken from which bone marrow or spleen cells were taken can a ect the transformed cell types seen (Zhang et al, 1989(Zhang et al, , 1991. Fifth, v-Rel-transformed cells can undergo continued di erentiation after establishment in vitro (Zhang et al, 1989). Sixth, in some cases, only very few in vitro-transformed colonies were analysed, which may have under-or mis-represented the cell-type transforming potential of v-Rel.…”