Autoimmune Terminology To Know For Your Next Doctor’s Appointment

A disease is a change from a state of health that causes harm to a body system or organ. You may also hear your healthcare provider call it morbidity (1). Autoimmune diseases are attacks from a person’s own immune system that weaken different parts of the body and affect their function (2, 3). The term condition is broader and refers to any state of a person that may require medical care. Conditions include diseases, but also injuries, psychological disorders, and even pregnancy. Condition is also used as a standard term by hospitals or clinics to refer to a patient’s status, such as stable, fair, or critical (4). You may sometimes hear the terms disease and condition being used interchangeably, but paying attention to context is key.

A comorbidity is the presence of two or more diseases in a person at the same time. In the realm of autoimmunity, polyautoimmunity is the coexistence of two autoimmune diseases, such as rheumatoid arthritis and autoimmune thyroiditis. Multiple autoimmune syndrome (MAS) is the coexistence of three or more autoimmune diseases (5).

A symptom is a subjective feature that can be experienced only by the affected person. Examples of symptoms in autoimmunity are joint pain, dizziness, and fatigue (1). A sign is an objective characteristic or physical finding that can be observed and measured by others, with autoimmune examples being swelling, rash, and fever (1). A syndrome is the collection of signs and symptoms that characterize a certain disease (1). In autoimmunity, an example of a syndrome is MAS, earlier defined as the presence of three or more autoimmune diseases at once.

A trigger is a factor that initiates the signs and symptoms of an autoimmune disease. “Trigger” and “cause” do not mean the same thing. While a cause creates the opportunity for a disease to develop, a trigger is the spark that activates it. Therefore, if an autoimmune disease is caused by a person’s autoantibodies or genes, triggers like food, pollution, or stress have the potential to activate the signs and symptoms of that disease. Different people may be sensitive to different triggers.

Autoimmune disease can often alter the cells of the immune system in a way that makes people more susceptible to infection, defined as the invasion of a body system or organ by microorganisms like viruses or bacteria. Although infection does not always cause disease (1), certain infections may be triggers of autoimmune disease signs and symptoms. Inflammation is a general response to tissue damage caused by infection but also by chemicals, heat, injury, or the immune system itself. While short-lived inflammation may be a beneficial process, long-lasting (chronic) inflammation can activate an autoimmune disease (1). For example, autoantibodies and T cells are known to be players in the inflammation process that leads to diseases like psoriasis.

In autoimmunity, flare-ups occur when signs and symptoms get dramatically worse in one or more organs of the body, often interfering with regular activities. Examples of severe flare-ups include nephritis in systemic lupus erythematosus, blurred vision and slurred speech in multiple sclerosis, and painful plaques in psoriasis. Your healthcare provider may refer to flare-ups also as flares, bouts, outbursts, or episodes.

Immune dysregulation collectively refers to the abnormal changes that cause an imbalance of the immune system, leading to the development of autoimmune disease (6).

Antibodies are specialized proteins that defend your body. They recognize antigens, defined as substances that cause the body to generate an immune response. Examples of antigens are external factors like microbes and chemicals. Autoantibodies are antibodies that recognize antigens inherently present in the body of patients who have an autoimmune disease. These antigens are called autoantigens or self-antigens (6). Antigen-presenting cells (APCs) are immune cells that allow lymphocytes to recognize the pathogen and organize an immune response. APCs consume and break down pathogens, and then express antigens on their cell’s surface to allow other immune cells to recognize the foreign invader (7).

Cytokines are small proteins released by the body involved in cell communication; there are proinflammatory and anti-inflammatory cytokines (8). A cytokine storm refers to a severe immune response in which dangerously high levels of proinflammatory cytokines are released by the body, which can seriously harm a patient. This condition may be triggered by autoimmune diseases or pathogens, such as the SARS-CoV-2 virus (9).

Lymphocytes are white blood cells that are highly involved in autoimmunity. They include B and T cells. B lymphocytes, or B cells, are white blood cells that produce antibodies to fight specific pathogens (10). T lymphocytes, or T cells, are white blood cells in the body’s adaptive immune response. One major type of T cells are CD8+ T cells, also called cytotoxic T cells, which can kill infected cells. Then, CD4+ helper cells can recognize antigens of foreign substances and then release cytokines to cause B cells to differentiate into antibody-producing plasma cells (11).

IgE, or immunoglobulin E, is an antibody often produced when the body has an allergic reaction (12). IgG, immunoglobulin G, is the most common class of antibodies, and they make up 75% of the antibodies found in the blood serum (13). IgM, or immunoglobulin M, is the first antibody produced by the body in response to infection and enhances the body’s ability to remove dead cells (14).

ANA tests determine the level of antinuclear antibodies in your blood; these antibodies attack the nuclei of healthy cells. ANA tests help diagnose autoimmune diseases such as lupus, rheumatoid arthritis, or scleroderma (15).

C-Reactive protein (CRP) tests measure the level of C-reactive protein in the blood. CRP levels in healthy individuals are generally low. The liver releases CRP into the blood in response to inflammation, so CRP tests can help monitor inflammation and to determine its cause. Inflammation may be due to bacterial or fungal infections or autoimmune diseases, like lupus and rheumatoid arthritis (16).

ELISA assays are immunological assays used to test for the presence of different antibodies, antigens, proteins, or hormones in a sample. These assays can identify specific cytokines and test for pregnancy and HIV, among many other conditions (17).

An erythrocyte sedimentation rate (ESR) test is a test for how quickly red blood cells, or erythrocytes, settle in a test tube with blood. Inflammation is a common symptom of autoimmune diseases, which causes red blood cells to settle faster than normal. An ESR test does not diagnose one disease but provides an indication that there is increased inflammation in the body, so it’s often used in combination with more specific tests (18).