Abstract
Affinity maturation of the humoral immune response is caused by single base changes that are introduced into the V regions of the Ig genes during a brief period of B cell differentiation. It has recently become possible to study V region mutation in some human Burkitt's lymphoma cell lines that mutate their V regions and express surface markers that suggest they arose from the malignant transformation of germinal center B cells. Ramos Burkitt's cells constitutively mutate their V regions at a rate of ∼2 × 10-5 mutations/bp/generation. However, the sequencing of unselected V regions suggested that our Ramos cell line was progressively losing its ability to undergo V region hypermutation. To accurately quantify this process, subclones with different nonsense mutations in the μ heavy chain V region were identified. Reversion analysis and sequencing of unselected V regions were used to examine the clonal stability of V region hypermutation. Even after only 1 month in culture, stable and unstable subclones could be identified. The identification of mutating and non-mutating subclones of Ramos provided a unique opportunity to identify factors involved in the mutational process. Differential gene expression between mutating and non-mutating Ramos clones was examined by RT-PCR and cDNA microarray analyses. We found that the expression of activation-induced cytidine deaminase (AID), a putative cytidine deaminase, correlated with mutation rates in Ramos subclones. These results suggest that the hypermutation phenotype is inherently unstable in Ramos and that long culture periods favor outgrowth of non-mutating cells that express lower levels of AID.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1175-1184 |
| Number of pages | 10 |
| Journal | International Immunology |
| Volume | 13 |
| Issue number | 9 |
| State | Published - 2001 |
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Keywords
- Antibody
- B lymphocytes
- Burkitt's lymphoma
- Somatic mutation
ASJC Scopus subject areas
- Immunology
Cite this
Clonal instability of V region hypermutation in the Ramos Burkitt's lymphoma cell line. / Zhang, W.; Bardwell, P. D.; Woo, C. J.; Poltoratsky, V.; Scharff, Matthew D.; Martin, A.
In: International Immunology, Vol. 13, No. 9, 2001, p. 1175-1184.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Clonal instability of V region hypermutation in the Ramos Burkitt's lymphoma cell line
AU - Zhang, W.
AU - Bardwell, P. D.
AU - Woo, C. J.
AU - Poltoratsky, V.
AU - Scharff, Matthew D.
AU - Martin, A.
PY - 2001
Y1 - 2001
N2 - Affinity maturation of the humoral immune response is caused by single base changes that are introduced into the V regions of the Ig genes during a brief period of B cell differentiation. It has recently become possible to study V region mutation in some human Burkitt's lymphoma cell lines that mutate their V regions and express surface markers that suggest they arose from the malignant transformation of germinal center B cells. Ramos Burkitt's cells constitutively mutate their V regions at a rate of ∼2 × 10-5 mutations/bp/generation. However, the sequencing of unselected V regions suggested that our Ramos cell line was progressively losing its ability to undergo V region hypermutation. To accurately quantify this process, subclones with different nonsense mutations in the μ heavy chain V region were identified. Reversion analysis and sequencing of unselected V regions were used to examine the clonal stability of V region hypermutation. Even after only 1 month in culture, stable and unstable subclones could be identified. The identification of mutating and non-mutating subclones of Ramos provided a unique opportunity to identify factors involved in the mutational process. Differential gene expression between mutating and non-mutating Ramos clones was examined by RT-PCR and cDNA microarray analyses. We found that the expression of activation-induced cytidine deaminase (AID), a putative cytidine deaminase, correlated with mutation rates in Ramos subclones. These results suggest that the hypermutation phenotype is inherently unstable in Ramos and that long culture periods favor outgrowth of non-mutating cells that express lower levels of AID.
AB - Affinity maturation of the humoral immune response is caused by single base changes that are introduced into the V regions of the Ig genes during a brief period of B cell differentiation. It has recently become possible to study V region mutation in some human Burkitt's lymphoma cell lines that mutate their V regions and express surface markers that suggest they arose from the malignant transformation of germinal center B cells. Ramos Burkitt's cells constitutively mutate their V regions at a rate of ∼2 × 10-5 mutations/bp/generation. However, the sequencing of unselected V regions suggested that our Ramos cell line was progressively losing its ability to undergo V region hypermutation. To accurately quantify this process, subclones with different nonsense mutations in the μ heavy chain V region were identified. Reversion analysis and sequencing of unselected V regions were used to examine the clonal stability of V region hypermutation. Even after only 1 month in culture, stable and unstable subclones could be identified. The identification of mutating and non-mutating subclones of Ramos provided a unique opportunity to identify factors involved in the mutational process. Differential gene expression between mutating and non-mutating Ramos clones was examined by RT-PCR and cDNA microarray analyses. We found that the expression of activation-induced cytidine deaminase (AID), a putative cytidine deaminase, correlated with mutation rates in Ramos subclones. These results suggest that the hypermutation phenotype is inherently unstable in Ramos and that long culture periods favor outgrowth of non-mutating cells that express lower levels of AID.
KW - Antibody
KW - B lymphocytes
KW - Burkitt's lymphoma
KW - Somatic mutation
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UR - http://www.scopus.com/inward/citedby.url?scp=0034813325&partnerID=8YFLogxK
M3 - Article
VL - 13
SP - 1175
EP - 1184
JO - International Immunology
JF - International Immunology
SN - 0953-8178
IS - 9
ER -