Characterization of a New Antigen Expressed by B and Myeloid Lineage Cells Identified by the Monoclonal Antibody LIP-6

The LIP-6 MAb was produced against the undifferentiated cell line bh2-1 and recognizes an antigen expressed on all pre-B and B cell lines tested and some myeloid lineage lines. FACS analysis of normal tissues showed that LIP-6 is expressed on B lineage cells at all stages of differentiation, from bone marrow pre-B to plasma cells. T cells and thymocytes are LIP-6−, and splenic CD11b+cells are heterogeneous for LIP-6 expression. The LIP-6 MAb was shown to precipitate a major 75-kDa and a minor 85-kDa protein under reducing conditions and a large protein of >240 kDa under nonreducing conditions. Removal of N-linked sugars from the reduced lysates resulted in a single 65-kDa protein, suggesting that there is differential glycosylation of a single 65-kDa protein that forms disulfide-linked multimers. Finally, the LIP-6 antigen was shown not to be linked to the cell surface via a GPI linkage.