About Lymphoma > Immune System Glossary

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Glossary | Diagnostic terms | Genes | Lymphatic System | Lymphoma Simplified | Remission & Response | Treatment background 

Also see General Abbreviations & Acronyms-  remission.org 
Clinical Research and Good Clinical Practice Dictionary (Glossary of Terms and Acronyms) - med.umich.edu

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We update this list in response to visitor questions.

active immunity  is an acquired immunity in which the immune system recognizes an antigen as foreign and generates an attack on the invading pathogen or abnormal cell that expresses the antigen (a unique protein signature).  The goal of cancer vaccines is to induce active immunity against unique proteins specific to the tumor cells. Here the immune system "learns" about the identity of part of the tumor and "remembers" this information in order to produce a sustained attack and long-term surveillance against the cancer cells. 

agammaglobulinemia - a deficiency or lack of immunoglobulins, or antibody.

allergen - a substance that causes an inappropriate reaction by the immune system to normally harmless substances.

anaphylactic shock - a life threatening allergic reaction causing swelling, difficulty breathing, and a drop in blood pressure.

anergy - describes an unresponsive state of immune cells to antigen stimulation.

adaptive Immunity (specific immunity) is a response to a specific immune stimulus (antigen) that involves cells of the immune system and frequently leads to a state of immune memory. The adaptive immune system marshals antibodies and T cells that are highly specific for a particular pathogen (or antigen). Once created, the antibodies and T cells can eliminate the pathogen if it appears even years later - so-called immune surveillance.

antibody (Ab) - a protein molecule (also called an immunoglobulin) secreted by B cells in response to an antigen (Ag). When an antibody attaches to an antigen, it destroys the antigen. Picture-it

Antibody-dependent Cell-mediated Cytotoxicity (ADCC) - An immune response triggered by  the presence of antibody  (Abs) coating the target cell (such as Rituxan). Upon binding its antigen, the Antibody's Fc region is exposed and will bind its receptor on the NK cell (or other effector cells) to form a bridge. Once the bridge is formed, a poorly understood lytic (killing) signal is delivered to the target cell by the effector cell, resulting in its demise. - (adapted from the Merck Manual)  Picture-it

antigen - the portion of a foreign substance or germ that can cause the immune system to become active against it. Picture-it  Also from Merck Manual: "Substances that stimulate an immune response in the body are called antigens. Antigens may be contained within or on bacteria, viruses, other microorganisms, or cancer cells. Antigens may also exist on their own—for example, as pollen or food molecules. A normal immune response consists of recognizing a foreign antigen, mobilizing forces to defend against it, and attacking it."
 
antigen presenting cell (APC) - immune cells - such as b-cells, macrophages, and dendritic cells -  that recognize foreign antigens, and present it to T-cells to initiate an immune response. 

antigen receptors - molecules on the surface of b- and t-cells that allow the cells to engage a specific antigen in the body in order to mount an immune response that is specific to the foreign molecule it binds to. Picture-it

antibiotics - Medicines used to treat some bacterial diseases.
 
apoptosis is a natural mechanism by which cells "commit suicide" when they have outlived their purpose, become defective, or have aged.  Apoptosis prevents cells from accumulating and forming tumors.  Understanding of the control of apoptosis in normal and malignant cells will help to improve the diagnosis and treatment of malignancies. The goal of many treatments, including chemotherapies is to induce malignant cells to undergo apoptosis.  Picture it   

Analogy:  Chances are you've seen a movie with apoptosis as part of the plot ... in almost any James Bond film.  

A fortress containing classified information is rigged for destruction by the owners if the security of the building is compromised. The process requiring a series of commands, which are relayed from one authorized person to another. This to prevent a programmed self-destruction by a careless mistake or a rouge individual. 

The fail safe system is carried out from within by specialists, and regulated by others. The trigger is not pulled until all the criteria is met: the security threat is real and it can't be corrected; the command has been given by authorized individuals and verified by others, and the actions carried out by specialized personnel. 

The security breach starts a chain of events (a cascade); each player communicating to the other until the big red button is pushed and the building destroyed; the sensitive information within it evaporating.

Similarly, our cells are rigged for self destruction when they become old or defective. The main purpose is to protect the body against replication of defective cells; and to remove old cells. 

The program for cellular self-destruction is called apoptosis, which is a type of quality control. The old or defective cells "take one for the team." That some cells die and other live on to replicate helps achieve a balance in the body. If individual cells just replicated and never died, our organs would never cease growing.

What happens in a cancer cell is that some parts of the cell machinery that carry out, signal for, or authorize apoptosis no longer function ... because of damage to genes that produce proteins that regulate or carry out these functions.

Many chemotherapy treatments are designed to exploit apoptosis ... by causing sufficient damage to the cells that force the issue, magnifying the urgency to self-destruct. Waking up the components in the cell that authorize apoptosis, such as the P53 gene.

One way the Rituxan might work is by changing the balance of signals in the cells it binds to to favor apoptosis. Shifting the balance to self destruct without causing damage. (Rituxan may also flag bound cells for destruction by effector cells, which is not dependent on apoptosis.)

Some investigational targeted agents are designed to wake up or silence parts of the cell that carry out or block apoptosis. ...

Imagine that a key protein within the cell is overactive and is giving a STOP order. Then imagine a small molecule drug that fits the shape of this protein, stopping the STOP order. This class of drugs target inhibitors of apoptosis. (Note: If normal cells utilize the same or similar proteins to carry our normal cellular functions, you may have side effects.) ~ KarlS

attenuated - no longer capable of causing infection, as in an attenuated virus to make a vaccine.  Also means weakened.

autoantibody - an antibody that reacts against the body's own tissue.
 
autoimmune disease - a disease that results when the immune system mistakenly attacks the body's own tissues. Examples: Rheumatoid arthritis, systemic lupus erythematosus, and type 1 diabetes. Picture-it

b-cells (also called B lymphocytes) - a type of white blood cells that come from bone marrow and develop into plasma cells, mature B cells capable of producing antibody. Picture-it  Each b-cell is capable of making an antibody specific to the triggering antigen.  The antigen trigger causing it to produce numerous plasma cells capable of manufacturing the antibody.

Biological marker (biomarker): A characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. www.fda.gov/cder/guidance/6400fnl.pdf   

bronchi - airways in the lungs

CD (clusters of differentiation)- As b-cells mature, they express different protein receptors on their surface. Some of these receptors can be used as treatment targets. These proteins or antigen markers are called Clusters of Differentiation (CD).

cell - building block that makes up tissues, organs, systems, and blood of the body.

chemokines are molecules released by pathogens and infected tissues that attract lymphocytes 

chromosome - physical structure in a cell that contains genes. Almost every human cell has 23 pairs of chromosomes.

complement - a series of blood proteins whose action "complements" the work of antibodies. Complement destroys bacteria, produces inflammation, and regulates immune reactions.

complement-dependent cytotoxicity (CDC): A mechanism of killing cells in which antibody bound to the target cell surface fixes complement, which results in assembly of the membrane attack complex that punches holes in the target cell membrane resulting in subsequent cell lysis. Picture-it | Picture-it

cytokines are molecules released by cells to alter lymphocyte function. 

DNA - Deoxyribonucleic acid - the basic instruction set for the development and activities of cells.
is like a library which contains thousands of books, called genes. DNA exists in all cells except mature erythrocytes. DNA is made up of bases (nucleotides) that are arranged in a specific sequence. The specificity of the sequence accounts for the production of a specific protein. 

effector cells perform a specific function in response to a stimulus; usually used to describe cells in the immune system (such as NK- and Cytotoxic T-cells)  that are activated to kill a pathogen or a cancer cell.  Also see Antibody-dependent Cell-mediated Cytotoxicity above.

etiologies are the causes of disease.

epigenetic refers to the regulation of gene expression - how, when, where, how much, etc.. Two key areas of epigenetic control are and Chromatin Remodeling and DNA Methylation. 

epitope  refers to the minimal structural unit of an antigen, recognizable for antibodies and lymphocyte antigenic receptors. 

familial describes a trait or disease that is observed with higher frequency within the same family, whether the etiology [cause] is genetic or environmental, or a combination of the two. Where a hereditary disease is one that is caused by a genetic trait.

gene - a unit of genetic material that is inherited from a parent. A gene carries the directions a cell uses to perform a specific function, like making proteins. Genes are made of DNA, the basic chemical unit of life. Genes contain the instructions or recipes for the creation (expression) of unique proteins that carry out cellular functions, such as divide, migrate, or die. 

germline mutation - a mutation (genetic defect) that is inherited from your parents.  Compare with a somatic mutation, which is acquired by chance or by exposure to toxins. The majority of cancers result from somatic mutations.

Graft vs Disease (GvD) - the action of donor cells against the cancer cells following a stem cell translant. 

Graft vs Host Disease (GvHD) - a sometimes serious complication of stem cell transplants  in which cells from a donor attack organs of the body.  Also see GvHD

granulocyte - a cell filled with potent chemicals that destroy germs and reduce inflammation.

hepatitis - a liver disease.

HLA stands for Human Leukocyte Antigens.  These proteins are unique markers found on the surface of nearly every cell in the body, and are in especially high concentrations in white blood cells.  

histiocytic -connective tissue containing large white blood cells

humoral immunity - mainly involves b-cells, with the cooperation of helper t-cells.  Like macrophages, b-cells take in and process antigens recognized as not belonging in the body.  Unlike macrophages, a b-cell can bind only to an antigen that matches it's antibody receptor (idiotype).  When helper t-cell signals are present the antigen exposed b-cell will multiply, and soon differentiate into plasma cells that create vast quantities of identical antigen-specific antibodies.  Released into the blood, the antibodies lock onto matching antigens, which may trigger complement-dependent cytotoxicity (CDC) and/or  antibody-dependent cell-mediated cytotoxicity (ADCC). 

hypermethylation - [a term describing the activity of genes] can cause oncogenes to produce proteins that cause malignant behavior. Chromatin Remodeling - Protein fibers called histones that interact with DNA. Drugs that inhibit histone deacetylases, for example, may enable expression of tumor suppressor genes.

hyperplasia (hye-per-PLAY-zha) - An abnormal increase in the number of cells in an organ or tissue. (source NCI)

hypomethylation - [ [a term describing the activity of genes]  can quiet genes that normally suppress cancer (tumor suppressor genes). 

IgA, immunoglobulin A - a type of antibody concentrated in mucous membranes and body fluids like tears, saliva, and secretions of the respiratory and gastrointestinal tract.

IgG, immunoglobulin G - the major antibody found in the blood that can enter tissues. It coats germs, helping other cells to seek and destroy them.

IgM, immunoglobulin M - an antibody that remains in the bloodstream where it can kill bacteria that enter the blood stream.

immunoglobulins - a large family of proteins, also known as antibodies. There are five classes of immunoglobulins: IgA, IgM, IgG, IgD, and IgE.  Picture-it

immune response - reactions of the immune system to foreign substances.

immune system - complex network of specialized cells and organs that has evolved to defend the body against attacks by foreign invaders.

immunity - protection from disease-causing microbes or pathogens.

immunization - the process of inducing protection (immunity) against the destructive forces of a disease-causing microbe.

immunoblastic - large lymphocyte that has been stimulated by an antigen

Immunophenotyping: tests that reveal the kinds of surface molecules that are present on cells (typically immune cells), such as CD20, CD22.  CDs stand for clusters of differentiation, which show the developmental stage of the cell and the cell type.  CD20, for example, is expressed only on mature b-cells, but not t-cells. 

Innate immunity (non-specific immunity) - consists of the pre-existing and fast-acting defenses of the body, such as skin, mucous, cilia, cytokines, and other secretions.  It may be that innate immunity also emits signals that activate adaptive immunity.

Induction therapy typically consists of conventional doses of chemotherapy administered in an attempt to reduce the amount of cancer in a patient’s body prior to high-dose therapy to be followed by a stem cell transplant.

infection - a state in which microorganisms have taken residence and multiplied in body tissues.

inflammation - an immune system reaction to stop the progression of disease-causing microbes, sometimes seen at the site of an injury. Signs of inflamation include redness, swelling, and heat.

Leukemogenic* therapies. - * "The risk of leukemia was greatest four or five years after chemotherapy began, and the risk was elevated for at least eight years after the cessation of chemotherapy. The drugs cyclophosphamide, chlorambucil, melphalan, thiotepa, and treosulfan were independently associated with significantly increased risks of leukemia, as was the combination of doxorubicin hydrochloride and cisplatin. Chlorambucil and melphalan were the most leukemogenic drugs, followed by thiotepa; cyclophosphamide and treosulfan were the weakest leukemogens, and the effect per gram was substantially lower at high doses than at lower doses. The extent to which the relative risks of leukemia are offset by differences in chemotherapeutic effectiveness is not known." http://content.nejm.org/cgi/content/abstract/322/1/1  

lymph nodes - small bean-shaped organs of the immune system, distributed widely throughout the body. They provide an environment where lymphocytes can receive initial exposure to foreign antigens (viruses, bacteria, fungi, etc.). This activates the lymphocytes to perform immune functions.  Most lymph nodes form in clusters throughout the system, such as in the neck, armpit, and groin.

lymphocytosis is an abnormal increase in the number of lymphocytes — a type of white blood cell — in your blood. The most common cause is viral infection, such as EBV, CMV, rubella, whooping cough, toxoplasmosis, brucellosis, chronic lymphatic leukaemiam, and leukemic phase lymphoma.

lymphoblastic  - immature lymphocyte - white blood cell in early stage of development.

lymphocytes - small white blood cells (B and T cells) that provide immune defense.

neoplasia (NEE-o-PLAY-zha) Abnormal and uncontrolled cell growth. (source NCI)

neutrophils - an important white blood cell that is both a phagocyte and a granulocyte abundant in the blood.

nodular - well-defined knot of tissue

macrophage - a large immune cell that gobbles microbes and presents antigens from the ingested pathogen to other immune cells.  To further orchestrate an immune attack, macrophages send protein signals none as monokines.

MHC molecules  - At the heart of immunity is the ability of immune cells to distinquish self from none self. So a fundamental question is how do immune cells do this? Is it by shape? Color? Scent? 

As it turns out cell-to-cell communication is a touchy/feely thing, and that when immune cells bump into other cells in the night they grope for a specific molecule called the MHC. Your immune cells can tell by feeling for the distinctive structure of this molecule (it's protein signature) if it's one of your own ... so the correct MHC is a password for safe passage in your body.   The diversity of the MHC molecule from one individual to another is sometimes referred to as polymorphism, and this diversity that's encoded onto each cell of your body is the reason transplanted tissue is typically rejected.

"One group of proteins encoded by the genes of the MHC are the markers of self that appear in almost all body cells. Known as class I MHC antigens, these molecules alert killer t cells to the presence of body cells that have been changed for the worse - infected with a virus or transformed by cancer - and that need to be eliminated. " 

"A second group of MHC proteins, class II antigens, are found on b cells, macrophages and other cells responsible for presenting foreign antigen to helper t cells. Class II products combine with particles of foreign antigen in a way that showcases the antigen and captures the attention of the helper t cells. "

Source: Understanding the Immune System ~ NIH:   Picture it 

microbes - bacteria, fungi, or virus that invades the body. Also called a pathogen.

molecule - The smallest physical unit made up of a chemical substance such as a protein or a fat. Molecules are the building blocks of a cell, and a gene determines how each molecule is produced.

mucous membrane - The moist lining of certain body cavities such as the mouth.

mutation - a change in a cell's DNA that may cause the cell to produce an abnormal protein.

methylation - is a hallmark of cancer. Specifically, it is the addition of a methyl group to specific cytosines (the components of DNA) that regulates gene activity. 

oncogenes - mutated and/or over-expressed versions of normal genes that can cause a cell to lose growth restraints, fail to differentiate (mature to a next stage), or prevent the cell from initiating the programmed cell death process called apoptosis. Some oncogenes turn on other genes that promote cancer.

opsonization - a process that identifies cells or bacteria to the phagocytic system (immune cells that engulf pathogens) that then and attack and engulf cells or bacteria that have been identified to them by the complement or antibody system. animation

opportunistic infections - infections caused by microbes that usually do not cause disease in healthy individuals, but which can result in overwhelming and widespread infection in people with immune deficiency.

palliative care - the goal is to achieve the best possible quality of life for patients and their families when the patients disease is not responsive to curative treatment.

pathogen is a disease causing microorganism 

phagocytes - large white blood cells that contribute to immune defense by engulfing microbes, such as bacteria and fungi, or other cells and foreign particles.

refractory is resistance to standard treatment.

RNA - In order for DNA to produce a protein, an intermediate step is required. In this step, DNA is transcribed into RNA (messenger RNA, or mRNA). The sequence of mRNA that encodes a protein is oriented in only one direction, which is known as the "sense" orientation.

Salvage therapy -- a term often applied to combinations of chemotherapy drugs used to treat lymphomas after relapse in which the patient is either not responsive to standard protocols, or the patient has general health consideration (allergies, lung, or heart problems) that require the use of unusual combinations of treatment agents, dosing or dosing schedules. Be aware that despite the negative connotation of "salvage," these novel treatments regimens can sometime achieve remissions. 

somatic mutation - a mutation (genetic defect) which is acquired by chance or by exposure to toxins. The majority of cancers result from somatic mutations. Compare with  germline mutations that are inherited from your parents. 

stem cell transplant (bone marrow transplant) - the goal of this treatment is to cure the patient with aggressive therapies that partially or completely kills off (ablates) the normal stem cells in the marrow -  the spongy tissue found in the cavities of the body's bones, where all the body's blood cells are produced. These cells are then replaced with the patient's own stem cells (harvested prior to treatment), or matched donor cells.

T cells (T lymphocytes) - white blood cells that either orchestrate the immune response (regulatory T cells) or directly attack infected or malignant cells (cytotoxic T cells).

tissue - a group of similar cells joined to perform the same function.

tissue type - the type of histocompatibility antigens on a person's cells or tissues. If the histocompatibility antigens do not match well, there is a much greater chance that the recipient will reject the donated tissue.

Titers is a measurement of the concentration of a substance in a solution. It usually refers to the amount of medicine or antibodies found in a patient's blood. 

Tolerance is a non-reactivity of the immune system to self. 

tumor suppressor genes - genes that protect cells from cancer. They may put the brakes on accelerated growth, or initiate cell death when DNA damage is detected. DNA damage. The under expression of tumor suppression genes can lead to malignant behavior.

Vaccinal effect - when a therapy leads to recognition of tumor antigens (abnormal proteins) as foreign leading to attack of remaining tumors by t-cells.

vaccine - substance that contains parts of antigens from an infectious microbe. By stimulating an immune response (but not disease), it protects the body against subsequent infection by that organism.