IgM-Fcα/μR Interaction
Introduction of Fcα/μR
IgM is the first antibody to be produced in a humoral immune response and may play an important role in the primary stage of immunity. Fc receptors play important roles in a wide array of immune responses. In contrast to the well-defined Fcγ and Fcε receptors, the structural and functional characteristics of Fc receptors for IgM expressed on hematopoietic cells remained incompletely understood for years, although a polymeric immunoglobulin receptor (poly-IgR) that is able to bind IgM and IgA and expressed on epithelial cells was characterized. Functional Fc receptors for IgM were suggested since the early 1980s to exist on subpopulations of human and rodent lymphocytes. However, molecular cloning of an Fcμ receptor gene was not successful for years. Similarly, although a human Fcα receptor (FcαRI) was described, a homologous rodent Fcα receptor had not been identified. In 2000, Fcα/μR became the first Fc receptor for IgM as well as IgA, described in both humans and rodents, and expressed on both hematopoietic and nonhematopoietic cells.
Expression of Fcα/μR
Fcα/μR is expressed on a subset of B cells and macrophages, but not on granulocytes, T cells, or NK cells in the mouse spleen. Although Fcα/μR is closely related to poly-IgR, the expression pattern of Fcα/μR is quite different from that of poly-IgR, which is expressed on epithelial, but not hematopoietic, cells. During developmental stages of B cells in the bone marrow, IgD+, IgM+ mature B lymphocytes expressed significant amounts of the mFcα/μR. In contrast, it was not expressed on the majority of IgD, IgM+ immature B lymphocytes, suggesting that the Fcα/μR might be involved in B cell development. However, recent evidence demonstrated that each lymphocyte population, including B cell subsets, was normal in mice deficient in Fcα/μR gene, suggesting that Fcα/μR defect did not affect lymphocyte development. Unlike mFcα/μR, hFcα/μR is hardly detected on the cell surface of B cells and monocytes in peripheral blood. Immunohistochemical studies demonstrated that the Fcα/μR is expressed in germinal centers in lymphoid tissues, including spleen, lymph nodes, and Peyer s patch, strongly suggesting that Fcα/μR may play an important role in humoral immune responses.
The COVID-19 IgM/IgG antibody test is designed for the qualitative indication of past or present infection by the SARS-COV-2 virus.
It detects IgG /IgM antibodies in response to the CoV-2 virus.
It is a single-use self contained test that identifies past infections or presumed immunity, active infections, and a negative result in 15 minutes.
The antibody test is very different from the molecular covid19 test, which is done with a nasal swab and is checked for the presence of the covid-19 virus itself.
This test is the most sensitive testing approach and can identify the virus before symptoms are expressed.
Medical PPE Resource has submitted the COVID-19 IgM/IgG antibody test for FDA Emergency Use Authorization (EUA).
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