Immunoglobulins (Ig), also known as antibodies, are glycoproteins synthesized by plasma cells in response to specific immunogens, such as bacterial proteins. These antibodies play a crucial role in humoral immune responses against various pathogens, including bacteria, viruses, fungi, and parasites, as well as cellular antigens, chemicals, and synthetic substances.
When an immunogen or antigen interacts with a B cell receptor (BCR) on the surface of B cells, it triggers a signaling cascade that leads to the differentiation of B cells into plasma cells. These plasma cells produce antibodies that are highly specific to the immunogen, forming a critical component of the immune response.
The structure of immunoglobulins consists of two light chains and two heavy chains arranged in a light-heavy-light-light structure. The heavy chains vary between classes and contain functional regions known as the Fc region, responsible for biological functions like binding to cell receptors, and the Fab region, which contains antigen-binding sites. The chains are folded into domains, with the heavy chain typically having four or five domains and the light chain having two domains. The hypervariable regions (HRRs) within the domains contain the antigen-binding sites, ensuring specificity in antibody-antigen interactions.
The functions of immunoglobulins are multifaceted, including activating the complement system, opsonizing microbes to facilitate phagocytosis, preventing microbial attachment to mucosal surfaces, and neutralizing toxins and viruses.
Immunoglobulin deficiencies can lead to various disorders, impacting the immune system's ability to effectively combat infections. Patients with immunoglobulin deficiencies may present with recurrent infections, autoimmune diseases, or allergic conditions. Improving care coordination among the interprofessional healthcare team is crucial to enhancing the care of immunoglobulin-deficient patients, ensuring timely diagnosis, appropriate treatment, and comprehensive management of their condition.
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