Anti-FBL monoclonal antibody, clone FQS21934(C)

Heterogeneity of V-alpha-1+ and V-beta-10+ TCR alpha-beta-chains, which are predominantly used in anti-FBL-3 CTL clones established in vitro, was investigated at a nucleotide level in FBL-3 tumor-infiltrating lymphocytes (TIL) in vivo. The majority (90%) of V-beta-10+ beta-chains dominated in TIL used homogeneous V-beta-10D-beta-2.1 sequences identical to that used in the T cell clones with cytotoxic functions. The homogeneous TCR beta-chain expression was dominant and found to be about 10% of the total TCR beta-chains in the TIL population, which was a > 300- to 900-fold increase than in the regional lymph nodes. This is in good agreement with the in vitro data showing that about 11% CTL clones used the homogeneous V-beta-10D-beta-2.1+ beta-chain. However, the J-beta segment does not seem to contribute greatly to the recognition and selection of this TCR because some of homogeneous VD+ beta-chains were associated with J-beta segments other than J-beta-2.7 of the CTL clones. The frequency of the V-alpha-1J-alpha-112-2+ alpha-chain expression of the CTL type was much less (3- to 80-fold increase compared to that of lymph node) and also varied in sample materials, indicating the lower contribution of the alpha-chain for the oligoclonality of the TCR. The results were also confirmed by quantitative PCR and RNase protection assays. This suggests that the dominant expression of the homogeneous TCR beta-chain is due to the expansion of the particular anti-FBL-3 CTL in the tumor in situ. Also, the TCR beta-chain, especially the V-beta-D-beta region, rather than alpha-chain is more important for the recognition and selection of the anti-FBL-3 TIL with cytotoxic functions.

Background. Dysregulation of ribosome biogenesis and alteration of ribosome composition, including alteration in ribosomal RNA (rRNA) 2'-O-ribose methylation, can playa role in malignant transformation and cancer progression. Several studies recently reported that components of the rRNA methylation complex are associated with leukemogenesis. However, no study ever investigated the alteration of ribosome biogenesis factors in the most common pediatric malignancy - B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Objectives. The objective of this study was to examine the expression of factors building the rRNA methylation complex, either the protein components (1 methyl-transferase (FBL), NOP56, NOP58, NHP2L1) or some RNA components (box C/D snoRNAs: SNORD35B,SNORD65,SNORD46,SNORD50A,SNORD38B), as well as CMYC, and nucleolin (NCL) - a protein involved in rRNA synthesis. Clinical effects in children with BCP-ALL were also investigated. Material and methods. The factors involved in ribosome biogenesis were studied in 28 children with BCP-ALL with the use of real-time polymerase chain reaction (RT-PCR) using the BioMark HD System (Fluidigm, San Francisco, USA) in cDNA prepared from the bone marrow samples collected at diagnosis. Results. Strong correlations were observed between NOP56, NOP58 and NCL, and multiple weaker correlations were observed in the box C/D snoRNA category, and between box C/D snoRNA and transcripts coding proteins of the rRNA methylation complex. The expression of analyzed transcripts did not correlate with the initial white blood cells count (WBC) or with bone marrow blast percentage. Ribosome biogenesis upregulation with overexpression of FBL and NOP56, and CMYC was found in patients who subsequently relapsed and the upregulation signature was not associated with known risk predictors. Conclusions. This is the first report on the clinical aspect of ribosome biogenesis in pediatric BCP-ALL, and it shows that overexpression of CMYC and C/D box nucleoproteins FBL and NOP56 is an antecedent event in patients who subsequently relapse. The dysregulation pattern is different from the previous reports in acute myeloid leukemia (AML), suggesting that dysregulation of ribosome biogenesis is specific for BCP-ALL.