Brain Facts:
Immune System

Histamine

Histamine is a chemical normally secreted by cells on the immune system, causing allergic reactions such as sneezing and itching (which is why we take antihistamines to relieve allergic symptoms).

Immune System
—Components

The immune system is made up of the spleen, the bone marrow, the lymph nodes, and various kinds of white blood cells, some of which circulate throughout the body, while others reside in the various tissues of the body, including skin.

Immune System
—Key Property

A key property of the immune system is that its cells move. Unlike brain cells, which, for the most part, do not more, the cells of the immune system do their job by traveling throughout the organism to wherever they are needed to mount a defense or repair damage.

Immune System
—Purpose

The immune system's overall purpose is to defend against pathological invaders that threaten the health of the organism and to repair any damage they cause. To do this, the immune system must define the boundaries of the organism, distinguishing between what is self and what is not self, that is determining what is part of the organism and needs to be repaired and restored versus what is part of a tumor and needs to be killed.

Immune System
—Stress

The stress response helps equip your white blood cells, sending them off to fight on the body’s most vulnerable fronts, such as the skin. Acute stress can even make you respond better to a flu shot. But chronic stress reverses these effects, decreasing you number of heroic white-blood-cell solders, stripping them of their weapons, even killing them outright. Over the long term, stress ravages parts of the immune system involved in producing antibodies. Together, these can cripple your ability to fight infection. Chronic stress also can coax your immune system to fire indiscriminately, even at targets that aren’t shooting back—like you own body.

Immune System
—Stress - Sickness

People who experience chronic stress are sick more often. A lot more often. One study showed that stressed individuals were three times as likely to suffer from the common cold. People were especially vulnerable to the cold-producing virus if the stressors were social in nature and lasted more than a month. They also are more likely to suffer from autoimmune disorders, such as asthma and diabetes.

Immune
—Anti- NOGO-A Immunotherapy
Cognitive Recovery

In earlier studies, Kartje and her colleagues showed that anti-NOGO-A immunotherapy led to the recovery of forepaw and arm movement after induced stroke in aged rats. The new study found that the therapy also improved cognitive recovery when testing performance on a spatial memory task.

"This suggests that the NOGO-A protein limits the recovery of memory after stroke and that by blocking the protein, more recovery may occur," Kartje says. Her laboratory next plans to look for structural changes in the brain that underlie the recovery process.

Immune
—Anti- NOGO-A Immunotherapy

An experimental treatment called anti-NOGO-A immunotherapy has been found to improve performance on a test of cognitive ability after stroke in aged rats, according to a new study from a team of researchers led by Gwendolyn Kartje, MD, PhD, at Loyola University and the Edward Hines VA Hospital in Chicago. This finding may one day lead to more effective treatments for the millions of people worldwide who survive a stroke each year and for the millions of others suffering from Alzheimer's disease and other memory disorders.

Anti-NOGO-A immunotherapy blocks the NOGO-A protein, a molecule found in the brain. The precise role of this protein is unknown, but it appears to inhibit aberrant growth. When the brain becomes damaged, however, this inhibitory function turns harmful, preventing injured cells from regenerating and repairing themselves. It also prevents uninjured cells from changing to help with the recovery.

Immune
—Molecules

Studies indicate that immune molecules perform important functions in the brain, including how much or how quickly our brain changes in response to new experiences.

Immune
—Reducing The Expression of Immune System Protein

New research suggests that reducing the expression of an immune system protein in the brain may help repair neurons damaged by spinal cord injury and other trauma. Other research has uncovered the important role that immune molecules perform in the prenatal development of such diseases as autism and schizophrenia. Additional findings reveal that an innovative type of immunotherapy assists with the recovery of memory after stroke.

"The discovery that immune molecules play a crucial role in shaping neuronal connections and are even expressed on nerve cells important in learning and memory is opening up a whole range of potential new treatment targets for diseases in which these connections have gone awry, such as Alzheimer's and other dementias, autism, amyotrophic lateral sclerosis (ALS), Parkinson's disease, schizophrenia, and in nerve injury," says Esther Sternberg, MD, of the National Institutes of Health. "Understanding these neural immune connections at a molecular and cellular level will shed light on the reasons these diseases develop and will help provide new ways to prevent or treat them."

Interferons

Interferons are peptides that are made by certain white blood cells known as lymphocytes. Like antibodies, interferons have the job of fighting off invading pathogens and thus help to preserve the integrity of the body.

MHC class I
—Glial Cells

MHC class I also has an effect on the action of glial cells, which in turn may influence neurons in various ways. Although microglia, the "immune cells" of the central nervous system, responded more weakly in the absence of MHC class I molecules, other glial cells, known as astrocytes, responded more vigorously. If — and how — these different responses are linked with synaptic stripping is not yet known.

Neurons
—Paired-Immunoglobulin-Like Receptor-B (PirB),

More recently, Shatz and her team have reported that neurons also express an immune system protein called paired-immunoglobulin-like receptor-B (PirB), which, over time, gradually inhibits brain plasticity. Mice that lack PirB exhibit greater synaptic plasticity as they age — a finding that suggests that reducing PirB might help reestablish the connections among neurons damaged by spinal cord injury, stroke, or other trauma.

Neurotransmitter Acetylcholine
—Ileum

The Ileum, the upper part of the small intestine, contains the cholinergic nerve that releases the neurotransmitter acetylcholine.

Oxygen
—Electron Absorbing Sponge

The reason you don’t die of electron overdose is that the atmosphere is full of breathable oxygen. The main function of oxygen is to act like an efficient electron-absorbing sponge. At the same time the blood is delivering food stuffs to your tissues, it is also carrying these oxygen sponges. Any excess electrons are absorbed by the oxygen and, after a bit of molecular alchemy, are transformed into equally hazardous—but not fully transportable—carbon dioxide.

Study
—Aarhus  University Hospital in Denmark¾
Positive Thinking and Health

Researchers at Aarhus University Hospital in Denmark considered another possible mechanism for the connection between positive thinking and health—the immune system, the body’s means for fighting off infection. In looking at more than three hundred volunteers between the ages of seventy and eighty-five, they found that those who continually ruminated on negative thoughts had higher counts of white blood cells, as if their bodies were trying to fight off a disease. This suggests that negativity may have an adverse effect on health by actually stimulating a physiological response.