Identification of human plasma cells with a lamprey monoclonal antibody

Abstract

Ab-producing plasma cells (PCs) serve as key participants in countering pathogenic challenges as well as being contributors to autoimmune and malignant disorders. Thus far, only a limited number of PC–specific markers have been identified. The characterization of the unique variable lymphocyte receptor (VLR) Abs that are made by evolutionarily distant jawless vertebrates prompted us to investigate whether VLR Abs could detect novel PC antigens that have not been recognized by conventional Abs. Here, we describe a monoclonal lamprey Ab, VLRB MM3, that was raised against primary multiple myeloma cells. VLRB MM3 recognizes a unique epitope of the CD38 ectoenzyme that is present on plasmablasts and PCs from healthy individuals and on most, but not all, multiple myelomas. Binding by the VLRB MM3 Ab coincides with CD38 dimerization and NAD glycohydrolase activity. Our data demonstrate that the lamprey VLRB MM3 Ab is a unique reagent for the identification of plasmablasts and PCs, with potential applications in the diagnosis and therapeutic intervention of PC or autoimmune disorders.

Guidelines for the use of flow cytometry and cell sorting in immunological studies*

“…Note that this antibody is reactive with an epitope in the stalk region of all VLRB molecules, and it displays impaired antigen‐binding characteristics following modification with amine‐reactive dyes. Negative control monoclonal VLR4 antibody (specific for the BclA antigen of the exosporium of B. anthracis ). Positive control VLR32 antibody (specific for human CD5) or VLRB MM3 antibody (specific for human CD38 on plasma cells). Suitable cell lines for testing of positive controls are the Jurkat T‐cell leukemia and the Daudi Burkitt's lymphoma, respectively .…”

“…Very recently, a lamprey monoclonal antibody reacting with a unique epitope of the CD38 ectoenzyme was shown to be highly specific for ASCs. The antibody recognizes ASCs in tonsils, spleen, bone marrow and peripheral blood from healthy individuals and on most multiple myelomas .…”

“…r Positive control VLR32 antibody (specific for human CD5) [212] or VLRB MM3 antibody (specific for human CD38 on plasma cells). Suitable cell lines for testing of positive controls are the Jurkat T-cell leukemia and the Daudi Burkitt's lymphoma, respectively [209]. r Wash 2× with PBS/0.5% BSA.…”

“…Very recently, a lamprey monoclonal antibody reacting with a unique epitope of the CD38 ectoenzyme was shown to be highly specific for ASCs. The antibody recognizes ASCs in tonsils, spleen, bone marrow and peripheral blood from healthy individuals and on most multiple myelomas [209]. A staining pattern consisting of CD20 low /CD138 + /CD31 + was recently described; it detects bone marrow ASCs in rhesus macaques, a model which is frequently used for the evaluation of human vaccines.…”

Immunological memories of the bone marrow

“…While their precursors express CD38 at rather low levels, memory plasma cells express high levels of CD38 28, 29. This CD38 is apparently distinct from CD38 on other cells; it is selectively recognized by a plasma cell‐specific antigen receptor of lamprey, because it is dimerized and shows NAD glycohydrolase activity 30. Within CD38 high plasma cells of the bone marrow, further diversity has been described regarding expression of other surface molecules 28.…”