RESUMO
CD1A is a cell surface protein expressed on Langerhans cells and cortical thymocytes that could potentially be used as an immunotherapeutic target in Langerhans Cell Histiocytosis (LCH), the cortical subtype of T-cell acute lymphocytic leukaemia (T-ALL) and other CD1A-positive tumours. The monoclonal antibody (mAb) CR2113 was selected from a panel of six fully human mAbs isolated from a semi-synthetic phage display library, based on specificity and avidity against cells expressing CD1 antigen variants. CR2113 recognized CD1A in T-ALL cell lines and patient samples. Confocal microscopy revealed that the CR2113-CD1A complex was internalized at 37°C. Furthermore, while CR2113 induced moderate complement-dependent cytotoxicity (CDC), potent antibody-dependent cell cytotoxicity (ADCC) activity was observed against CD1A expressing cell lines as well as T-ALL cell lines and T-ALL patient samples. In vivo experiments showed that CR2113 as a naked antibody has modest but specific anti-tumour activity against CD1A-expressing tumours. CR2113 is a high-affinity human anti-CD1A mAb with significant ADCC activity. These properties make CR2113 a candidate for clinical diagnostic imaging and therapeutic targeting of LCH as well as potential use in other clinical applications.
Assuntos
Anticorpos Monoclonais/imunologia , Citotoxicidade Celular Dependente de Anticorpos/imunologia , Antígenos CD1/imunologia , Técnicas de Visualização da Superfície Celular , Animais , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Monoclonais Humanizados/imunologia , Anticorpos Monoclonais Humanizados/isolamento & purificação , Afinidade de Anticorpos/imunologia , Especificidade de Anticorpos/imunologia , Antígenos CD1/metabolismo , Linhagem Celular Tumoral , Humanos , Imunoglobulina G/imunologia , Cinética , Melanoma Experimental/imunologia , Melanoma Experimental/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Biblioteca de Peptídeos , Leucemia-Linfoma Linfoblástico de Células Precursoras/imunologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Anticorpos de Cadeia Única/imunologia , Anticorpos de Cadeia Única/isolamento & purificaçãoRESUMO
Evaluation of the immune responses induced by childhood vaccines requires measurement of T-cell, as well as antibody, responses. However, cellular immune responses are often not analyzed because of technical hurdles and the volume of blood required. Therefore, a sensitive and specific assay for antigen-specific T cells that utilizes a small volume of blood would facilitate new vaccine evaluation. We developed a novel assay for quantifying virus-specific CD8(+) T cells that combines the use of HLA-A2 immunoglobulin-based artificial antigen-presenting cells (aAPCs) for stimulation of antigen-specific CD8(+) T cells in whole blood with quantitative real-time reverse transcription-PCR (qRT-PCR) to detect gamma interferon (IFN-gamma) mRNA. This assay was optimized using a well-established cytomegalovirus (CMV) CD8(+) T-cell system. The aAPC-qRT-PCR assay had comparable sensitivity to intracellular cytokine staining (ICS) in detecting CMV-specific CD8(+) T cells with a detection limit of less than 0.004%. The assay was applied to the detection of low-frequency measles virus (MV)-specific CD8(+) T cells by stimulating blood from five MV-immune HLA-A*0201 donors with four different MV-specific peptides (MV peptide aAPCs). Stimulation with three of the MV peptide aAPCs resulted in significant increases in IFN-gamma mRNA ranging from 3.3- to 13.5-fold. Our results show that the aAPC-qRT-PCR assay is highly sensitive and specific and can be standardized for screening MV-specific CD8(+) T cells in vaccine trials. The technology should be transferable to analysis of CD8(+) T-cell responses to other antigens.