Identification of new cell surface antigens defined by monoclonal antibodies
A major research interest is to identify the membrane antigens recognized by novel monoclonal antibodies. For this purpose, we use several strategies.
- Affinity purification of cell lysates derived from positive cell lines. The lysates are then separated by SDS-PAGE and subjected to fingerprint or partial amino acid analysis.
- Screening of the antibodies on retroviral expression libraries. Positive cells are cloned, the integrated cDNA isolated and sequenced.
- Screening of the antibodies on available transfectant lines that express known and promising antigens on the cell surface.
Using these strategies we identified the following human cell surface antigens:
and several other antibody-defined antigens selectively expressed on the surface of rare cell subsets.
Identification of new extracellular ligands
An additional research interest is the identification of membrane-bound ligands of membrane molecules. For this purpose, we perform cell attachment assays with recombinant proteins resembling the extracellular domains of the receptor. A binding cell line will be used to prepare cell lysates that will be affinity-purified on immobilized receptors. The purified ligand will then be subjected to fingerprint analysis. Using a modified strategy, we identified human SIRPα1 and SIRPα2 to be receptors for CD47. In contrast, SIRPβ1 did not bind to CD47.
Clustering of novel antibodies in HCDM (previously HLDA) workshops
During the past Conferences on Human Leukocyte Differentiation Antigens (HLDA) and Human Cell Differentiation Molecules (HCDM), several antibodies from our group were clustered (CD nomenclature). Novel antibodies are expected to be clustered In the forthcoming HCDM/HLDA conferences.
- Prof. Dr. med. Handretinger
- DFG-Projekt: Beteiligung einer CD56+ mesenchymalen Stammzellpopulation an der humanen hämatopoetischen Stammzellnische in unterschiedlichen Knochenkompartimenten (eingereicht).