RESUMO
In human B cells, effective major histocompatibility complex (MHC) class II-antigen presentation depends not only on MHC class II, but also on the invariant chain (CD74 or Ii), HLA-DM (DM) and HLA-DO (DO), the chaperones regulating the antigen loading process of MHC class II molecules. We analysed immediate ex vivo expression of HLA-DR (DR), CD74, DM and DO in B cell chronic lymphocytic leukaemia (B-CLL). Real-time reverse transcription polymerase chain reaction demonstrated a highly significant upregulation of DRA, CD74, DMB, DOA and DOB mRNA in purified malignant cells compared to B cells from healthy donors. The increased mRNA levels were not translated into enhanced protein levels but could reflect aberrant transcriptional regulation. Indeed, upregulation of DRA, DMB, DOA and DOB mRNA correlated with enhanced expression of class II transactivator (CIITA). In-depth analysis of the various CIITA transcripts demonstrated a significant increased activity of the interferon-gamma-inducible promoter CIITA-PIV in B-CLL. Comparison of the aberrant mRNA levels with clinical outcome identified DOA mRNA as a prognostic indicator for survival. Multivariate analysis revealed that the prognostic value of DOA mRNA was independent of the mutational status of the IGHV genes. Thus, aberrant transcription of DOA forms a novel and additional prognostic indicator for survival in B-CLL.
Assuntos
Regulação Neoplásica da Expressão Gênica , Antígenos HLA-D/genética , Leucemia Linfocítica Crônica de Células B/genética , Proteínas Nucleares/genética , RNA Mensageiro/análise , Transativadores/genética , Transcrição Gênica , Idoso , Apresentação de Antígeno/genética , Antígenos de Diferenciação de Linfócitos B/genética , Estudos de Casos e Controles , Eletroforese em Gel de Poliacrilamida/métodos , Feminino , Antígenos HLA-DR/genética , Antígenos de Histocompatibilidade Classe II/genética , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Regiões Promotoras Genéticas , Modelos de Riscos Proporcionais , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodosRESUMO
Recently, we showed that Epstein-Barr virus (EBV)-positive gastric carcinoma (GC) forms a distinct clinicopathologic entity with a better prognosis due to lower incidence of lymph node metastases (LN+). Here we investigated whether in EBV-positive GC more pronounced activation of cellular immune responses is associated with absence of (micro)metastases. Twenty EBV-positive primary tumors (PT) (9 LN+) were matched with 28 EBV-negative GC (11 LN+) for T- and N-stage, gender, and age. The PT (n = 28) and its LNs were analyzed by EBER RNA in situ hybridization and by immunohistochemistry for MHC class I and II expression, for CD3, CD8, CD4, CD20, CD56, CD83, and Granzyme B (GzB) expression. In LN metastases of EBV-positive GC, the EBV genome is maintained, excluding tumor escape by virus deletion. All GC express MHC class I independently of EBV status. In comparison with EBV-negative GC, EBV-positive GC have higher expression of MHC class II on the tumor cells (P = 0.029) and a more extensive infiltrate (P < 0.0001) of activated GzB+ CD8+ T cells (P = 0.028), which is most abundant in those EBV-positive tumors that do not metastasize (P < 0.0001). In addition, in EBV-positive GC without metastases, the infiltrate contains higher numbers of mature dendritic cells (DC) (P = 0.018). At present, the antigenic target has to be determined. These data support the notion that local triggering of cellular immune responses in EBV-positive GC prevents lymph node metastasis formation.