Humoral Immunity

Humoral Immunity

Humoral immunity involves antibodies and B cellsThe basic structural and functional units of life..  The term humor just means fluids. Humoral immunity derives its name from the factA statement based on direct observation that is repeatedly confirmed. that immunoglobulins(Ig) Antibodies: Proteins produced by the immune system to target specific antigens. float in blood, a humor of the body.  Whereas cytotoxic immunity targeted mostly viruses and some bacteria, humoral immunity primarily targets allergens.

No matter what, the first step is for the pathogen or the allergen to enter the body.  This can happen in many ways. This picture shows the allergen fitting between these epithelial cells. It moves through the tight junctions here.  A dendritic cell that is roaming in the area drinks interstitial fluidThe fluid surrounding cells within tissues. via pinocytosis. It consumes the allergen.  The dendritic cell immediately ingests the allergen. Then, it digests the allergen and displays it on MHC Class II proteinsLarge molecules made of amino acids with various functions in the body..

So, these dendritic cellsImmune cells in the epidermis that help fight infections. cannot communicate directly with B cells. They can’t say, ‘Hey, I found this. Maybe you want to make the right immunoglobulin.’ But, a helper T cell can help the communication between the dendritic cell and the B cell.  The helper T cell searches through the B cells in a lymph node. It tries to find a B cell that displays an immunoglobulin fitting the allergen epitope.  Once it finds this specific B cell, the helper T cell stimulates the B cell to differentiate.

B cell Differentiation

The B cells are formed in the red bone marrow where they mature and become immunocompetent. They can also be found in the liverA large organ that produces bile, detoxifies blood, and stores nutrients., surprisingly conferring allergies from a liver donor to the  liver recipient.  These are the cells responsible for producing antibodies against foreign antigensMolecules on the surface of cells that trigger an immune response.. Once a B cell is exposed to a foreign antigen it becomes activated and undergoes cell division. One of the daughter cells becomes a memoryThe ability to store and recall information. cell. That is why you can be resistant to reinfection of say, chicken pox, once you have been exposed. These memory cells may live up to 20 years or longer.

Humoral Immunity

The other daughter cell has a different fate. It will continue to divide and produce an army of B cells. Each B cell will produce antibodies. These antibodies are secreted into general circulation. They seek out and destroy the antigen they were exposed to. Antibodies mark the target cellsCells with specific receptors for a hormone. for destruction by causing them to clump together. They smother the target cell surfaces. Antibodies act like beacons for complement proteins and phagocytes. They cause toxic cell by-products to precipitate out of solutionA homogeneous mixture of two or more substances..

But there are limitations to their defenses. B cells can only detect an obvious threat, like bacteria floating around in your blood. They can’t detect viruses and bacteria that infiltrate your cells. For this, another defense is mounted by adaptive of immunity.

Humoral Immunity

The initial response, or primary response, happens when someone first encounters an antigen. For example, eating peanuts for the first time might cause an itchy throat, a sign of this primary response. However, the secondary response, occurring upon subsequent exposure to the antigen, is when anaphylaxis becomes a risk. Memory cells, without repeating the cloning process, immediately produce immunoglobulins to trigger a strong immune response. It is essential to understand that a full-blown anaphylactic hypersensitivity requires at least two interactions with the antigen.

Another diagram in your textbook illustrates the difference between primary and secondary immune responses. The primary response is slow, taking weeks to reach peak antibody levels, and is short-lived. In contrast, the secondary response produces higher and longer-lasting levels of immunoglobulins. Immunoglobulins such as IgM and IgG play critical roles in hypersensitivities like anaphylaxis. These responses differ from those targeting pathogens like viruses.