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MEM-59 monoclonal antibody detects a CD43 epitope involved in lymphocyte activation
M Alvarado1, C Klassen, J Cerny
1Department of Immunology, Medical School Hannover, Germany.
Insights
This study explores CD43 antigen stimulation using the MEM-59 antibody, revealing its role in T cell activation and co-stimulation. MEM-59 promotes T cell proliferation and signaling, distinct from previous antibodies.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Previous T cell activation studies focused on the CD43 antibody L10, targeting a sialic acid-independent epitope.
- The CD43 molecule's role in T cell activation requires further investigation with different antibody specificities.
Purpose of the Study:
- To investigate the T cell activation potential of the CD43 monoclonal antibody (mAb) MEM-59, which targets a neuraminidase-sensitive epitope.
- To elucidate the mechanism of MEM-59-induced T cell activation and its relationship with CD3/T cell receptor (TcR) signaling.
Main Methods:
- Stimulation of peripheral blood mononuclear cells (PBMC) and T cell lines with MEM-59 mAb.
- Analysis of PBMC proliferation, intracellular calcium mobilization, and Fc receptor-independent activation.
- Investigation of physical association between CD43 and CD3/TcR complexes using cell lysates.
Main Results:
- MEM-59 mAb induced monocyte-dependent PBMC proliferation and synergistic effects with phorbol 12-myristate 13-acetate.
- F(ab')2 fragments of MEM-59 were effective in PBMC proliferation, indicating Fc receptor independence.
- MEM-59 triggered intracellular Ca2+ mobilization in PBMC and Jurkat T cells, with defective signaling in CD3/TcR-negative mutants.
- CD43 and CD3/TcR were found in a large complex, suggesting a physical association.
Conclusions:
- MEM-59 mAb activates T lymphocytes through a mechanism distinct from L10, involving Fc receptor-independent pathways.
- CD43 appears to function as a co-stimulatory molecule in T cell activation.
- A physical and functional association exists between CD43 and CD3/TcR signaling pathways, crucial for T cell-antigen-presenting cell interactions.
Abstract:
Previous studies on T cell activation via CD43 antigen stimulation were limited to the use of L10, a monoclonal antibody (mAb) recognizing a sialic acid-independent epitope on the CD43 molecule. Here we study the CD43 mAb MEM-59, which recognizes a neuraminidase-sensitive epitope on the CD43 molecule, for its ability to activate T lymphocytes. The antibody by itself is able to stimulate proliferation of peripheral blood mononuclear cells (PBMC) in a monocyte-dependent fashion, and to act synergistically with the mitogen phorbol 12-myristate 13-acetate. It is demonstrated that the monocyte dependence of MEM-59-induced proliferation of peripheral blood lymphocytes (PBL) cannot be attributed to cross-linking via Fc receptors on monocytes alone: F(ab')2 fragments of MEM-59 are at least as effective as intact IgG in the induction of PBMC proliferation. The effects of MEM-59 reported here are distinct in important ways from those reported for L10. Our proliferation data are extended by the observation that MEM-59 mAb induces mobilization of intracellular Ca2+ in PBMC and in the T cell line Jurkat, while the CD3/TcR-negative Jurkat derived-mutant J.TR3-T3.5 exhibits defective signaling compared to the parent cell line. Moreover, CD3 and CD43 are shown to be present jointly in a large complex in a mild detergent lysate of the T cell line HPB-ALL. These data indicate a physical and functional association between CD3/TcR and CD43 pathways, suggesting a role for CD43 as a co-stimulatory molecule in CD3/TcR signaling, especially in T cell-antigen-presenting cell interactions.
