United Kingdom (UK)
Recombinant monoclonal antibody to CD33. Manufactured using AbAb’s Recombinant Platform with variable regions (i.e. specificity) from the hybridoma M195.
UniProt Accession Number of Target Protein: P20138
Alternative Name(s) of Target: gp67; Siglec-3; Myeloid cell surface antigen CD33; Sialic acid-binding Ig-like lectin 3
Immunogen: The original antibody was generated by immunizing mice with live leukemic myeloblasts.
Specificity: This antibody binds CD33, which is a 67 kD glycoprotein expressed on monocytes, hematopoetic progenitors, early myeloid progenitor cells and myeloid leukemias (acute and chronic) but not expressed on mature myeloid cells, normal stem cells, other hemtopoietic cells and non hematopoietic human tissues.
Application Notes: This antibody is recommended for myeloid differentiation studies, diagnosis of acute non-lymphoid leukemia cells and therapeutic treatment of myelois leukemia. Specificity of this antibody to CD33 was determined using RIA and immunoabsorption. Immunoflurorescence assay showed that the antigen is not expressed on adult human tissues (PMID: 2716349). Flow cytometric analysis was used to confirm reactivity of M195 with fresh hematopoietic neoplasms in the blood or bone marrow. In combination with MY9, this antibody is useful in diagnosis of acute myelogenous leukemia(AML) (PMID: 2725060). Murine antibody M195 was used in the phase I trial of AML (PMID: 1999719). Humanized IgG1 and IgG3 versions of this antibody has higher apparent binding affinity for CD33 antigen than the chimeric and parent murine version (PMID: 1737932, 1458463). The increase in binding affinity resulted from eliminating an N-linked glycosylation site at residue 73 in the heavy chain variable region in the course of humanization (PMID: 8232322). Preliminary trials to treat AML with humanized antibody showed specific bone marrow targeting without an immunogenic response (PMID: 8124221).
Antibody first published in:
Tanimoto et al. Restricted Expression of an Early Myeloid and Monocytic Cell Surface Antigen Defined by Monoclonal Antibody M195. Leukemia (1989); 3(5):339-48. PMID:2716349
Note on publication:
Describes the restricted expression of a myeloid and monocytic cell surface antigen and its charaterization with this antibody.
Immunofluorescence staining of fixed U937 cells with anti-CD33 antibody M195 (Ab02050) Immunofluorescence analysis of paraformaldehyde fixed U937 cells on Shi-fix™ coverslips stained with the chimeric rabbit IgG version of M195 (Ab02050-23.0) at 10 µg/ml for 1h followed by Alexa Fluor® 488 secondary antibody (2 µg/ml), showing membrane staining. The nuclear stain is DAPI (blue). Panels show from left-right, top-bottom Ab02050-23.0, DAPI, merged channels and an isotype control. The isotype control was an unknown specificity antibody (Ab00178-23.0) followed by staining with Alexa Fluor® 488 secondary antibody.