How does complement connect the innate and adaptive immune responses?

Innate immunity: first line of defense against infectious agents; Most pathogens can be controlled before a declared infection occurs.

Adaptive immunity: takes action when innate immunity fails. Make a specific response for each infectious agent and keep memory of it (it can prevent reinfection).

Explanation:

The immune system has evolved to be able to identify the strangers and develop a protective response to the latter (cognitive and destructive processes).

Innate or natural immunity: it is present at birth, being the first line against invasive microorganisms. Its characteristics are: it is present for life, it is not specific, it lacks memory and does not change intensity with exposure. It is useful against pyogenic microorganisms, fungi and multicellular parasites and includes three components: 1) physicochemical: skin, mucous membranes, secretions and cilia, which perform a washing and continuous cleaning, 2) humoral: complement, lectin binding to mannan and opsonins additional as C-reactive protein and proteolytic enzymes and 3) cellular: neutrophils, eosinophils, mast cells and natural killer lymphocytes.

Complement: it includes a high number of serum proteins that are produced mainly in the liver, form cascades so that each activated component catalyzes the activation of several molecules of the next component, amplifying the response. The consequences are cell lysis, the production of proinflammatory mediators and the solubilization of antigen-antibody complexes. Activation of the complement system occurs through three different pathways (alternating, classical and mannan-binding lectin) that converge in the final common pathway that provides most of the biological activity.

Cellular mechanisms: Neutrophils participate in the destruction of bacteria and fungi. Upon activation, adhesion molecules facilitate their entry into tissues, moving to chemical attractants and phagocytizing microorganisms. Destruction is mediated by oxygen dependent and independent pathways.

acquired immunity: acquired as part of development, increases with age and with repeated exposures, has specificity and memory for what is called adaptive. Its components are antibodies and cells (lymphocytes) and protects against bacteria (including those that produce intracellular infections), viruses and protozoa. In general, innate and acquired immune responses are not activated independently but complement each other.

Antigen-Antibodies: Antigens are structures that generate an anti-response from the immune system that has 3 elements of union and recognition of these;

1) antibodies that are soluble glycoproteins belonging to the group of immunoglobulins produced by B lymphocytes and plasma cells,

2) T-cell receptors that are large glycoproteins that interact with the peptide epitope preserved and presented by the third element

3) which are the major histocompatibility complex (CMH) molecules.

Antibodies perform many functions and have numerous uses as biological and clinical instruments