What is humoral immunity?

Humoral immunity is one of two ways the body seeks to protect itself from disease.

Humoral immunity is a means by which the body protects itself from infection by producing antibodies that target foreign material in the bloodstream that is seen as potentially dangerous, marking it for destruction. It is part of the adaptive immune system, which is activated in response to a specific threat, as opposed to the innate immune system, which is continuously active but less effective. The other part of the adaptive system is cellular, or cell-mediated, immunity, in which cells release toxins to kill invaders or attack them directly, without the involvement of antibodies. Together, humoral and cellular immunities are designed to defend the body against a wide variety of threats that can compromise it.

How it works

Over the years, humoral immunity has helped to eradicate smallpox cases worldwide.

This form of immunity starts in specialized white blood cells, known as B cells, which are produced by the bone marrow. They recognize antigens, which are certain molecules – like some proteins – on the surface of a virus or bacteria. There are different types of B cells, each designed to respond to a specific antigen. When one is found, the B cell multiplies, producing large numbers of individuals that release antibodies designed to attach to the antigen on the invading organism; they essentially turn into tiny antibody factories in the blood, floating around to target as many invaders as possible. Once tagged by these antibodies, the invaders will be destroyed by other immune system cells.

A combination of antiretroviral drugs is needed to control HIV, rebuild humoral immunity and prevent opportunistic infections.

When the invader is removed, many of the B cells produced to counter that particular threat will die, but some will remain, taking up residence in the bone marrow and acting as a sort of “memory” of that attack. People are born with a set of innate immune responses designed to recognize different types of cells and organisms that can pose a threat to the body, but humoral immunity is acquired through exposure to viruses, bacteria, and other harmful substances. Over time, the body accumulates more “memories” of previous attacks by harmful microorganisms.

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long term immunity

Because flu viruses evolve rapidly, medical researchers must develop new vaccines each season.

The humoral immune response can produce lasting immunity to many infectious agents. When the body is attacked by an agent – ​​such as a virus – that it has not encountered before, it must start from scratch and typically takes several days to mount an effective immune response. During this time, the virus can multiply unchecked, causing an infection that can produce unpleasant and possibly dangerous symptoms. Only when the body has produced a large number of suitable antibodies can it fight the infection. If, however, it does encounter the virus again, it will usually be much better prepared, thanks to the retention of the B cells produced in response to the previous attack, and can start working to eliminate the invader immediately.


Those undergoing chemotherapy should take precautions to avoid germs, as the treatments greatly impair their immunity.

This immunological “memory” also functions like vaccinations and immunizations. People can be injected with dead or inactivated forms of a dangerous virus or bacteria that will stimulate a humoral immune response without posing any threat to the body. If, at some point in the future, that person is exposed to the real agent, there must be an immediate immune response that will eliminate it before it can do any serious harm.

Without some form of immunity, whether natural or artificial, infectious diseases can spread quickly among family members and others in the community.

Vaccination is more effective for some types of infection than others. A worldwide vaccination program against the smallpox virus managed to lead to its complete extinction in the wild, as it was not able to find a human host that was not immune. Unfortunately, some viruses mutate rapidly, causing changes to the compounds on their surfaces that the humoral immune system uses to recognize them. That’s why new flu vaccines must be continually developed. People vaccinated against this rapidly mutating virus may not be immune to a new strain that appears the following year because the chemicals on its surface have changed and will not be recognized as antigens by the body’s B cells.

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immune system problems

Humoral immunity is a means by which the body protects itself from infection by producing that target foreign material in the bloodstream.

When people develop problems with their humoral immunity, they are more susceptible to developing infection and disease. Conditions like HIV attack the immune system directly to make it less functional. Immunity can also be compromised by the use of certain medications, such as chemotherapy for the treatment of cancer and the drugs used to prepare people for organ transplantation. In individuals who have compromised immune systems, aggressive and prompt treatment of any infection is to prevent the body from being overwhelmed by something that it cannot fight.

Immunizations are one step in creating humoral immunity.

Another problem that can occur with the immune system is autoimmune disease. Normally, the system is able to chemically distinguish between substances that are part of the body and those that are not, and it will only respond to “foreign” substances. Sometimes, however, the system can mount an immune response to something that is a normal cell component in the body, treating it in the same way as an invading organism. This results in damage to tissues and is responsible for a number of serious diseases like rheumatoid arthritis, lupus, and celiac disease.

The Origin of the Term

The term “humoral immunity” comes from the fact that this type of immunity is mediated by cells that float in the blood and lymph, or “humors” of the body. When researchers first began to explore the concept in the 1800s, many of them believed in medical theories dating back to ancient times, which included the idea that the balance of the body was maintained with substances that flowed through the body and caused various effects. While the humors theory has since been debunked, it lingers on in medical terminology.

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