Glossary (I-L)



An antibody found in blood, tears, saliva, mucus, and gastric juices.

IgA Deficiency
A dysgammaglobulinemia characterized by a deficiency of IgA.

The most common antibody. It is found in the blood and fights bacteria and viruses.

IgG Deficiency
A dysgammaglobulinemia characterized by a deficiency of IgG.

An antibody found in the blood. It functions like IgG, but is formed earlier in the immune response.

Immune Complex Diseases
Group of diseases mediated by the deposition of large soluble complexes of antigen and antibody with resultant damage to tissue. Besides SERUM SICKNESS and the ARTHUS REACTION, evidence supports a pathogenic role for immune complexes in many other systemic immunologic diseases including GLOMERULONEPHRITIS, systemic lupus Erythematosus (LUPUS Erythematosus, SYSTEMIC) and polyarteritis nodosa.

Immune Response

The activity or response of the immune system against "foreign invaders".

Immune System
Cellular and molecular components having the primary function of distinguishing self from non-self and defense against foreign organisms or substances. The primary cellular components are lymphocytes and macrophages, and the primary molecular components are antibodies and Iymphokines. (From Dorland, 27th ed)

Immunoblastic Lymphadenopathy
A disorder characterized by proliferation of arborizing small vessels, prominent immunoblastic proliferations, and amorphous acidophilic interstitial material. Clinical manifestations include fever, sweats, weight loss, generalized lymphadenopathy, and frequently hepatosplenomegaly.

Immunodeficiency (Immune Deficiency)
A problem with the immune system that prevents an adequate immune response.

Immunoglobulin (gamma globulin)
See antibodies.

Immunologic Deficiency Syndromes

Immunologic Diseases
Disorders caused by abnormal or absent immunologic mechanisms, whether humoral, cell-mediated or both.

A doctor who treats people with immune system problems.

The study of the immune system.

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Immunoproliferative Disorders
Disorders characterized by abnormal proliferation of primary cells of the immune system or by excessive production of immunoglobulins.

Immunoproliferative Small Intestinal Disease

A spectrum of conditions ranging from a benign plasma cell hyperplasia to a highly malignant lymphoma of the small intestine.

Indwelling Pleural Catheters
A small catheter placed in the space around the lung (Pleural space) through a tunnel under the skin to drain fluid accumulated due to cancer and other diseases. This catheter can remain in the pleural space for an extended period of time (weeks to months) and can be used to drain the fluid as needed. The drainage is done at home, hospice or nursing home by the patient himself, family member or a visiting healthcare professional making the need for hospital visits or hospitalization unnecessary.

Causes infections.

Infectious Mononucleosis

The body's (immune system) protective response to an irritant. When there is injury or infection in the body the immune system responds and there is redness, warmth and swelling in the tissue. Chronic or long term inflammation causes the building of new connective tissue (thickening of the tissue) which can create many problems.

An acute viral infection involving the respiratory tract. It is marked by inflammation of the nasal mucosa, the pharynx, and conjunctiva, and by headache and severe, often generalized, myalgia.

The dispenser for metered-dose medications.

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The process of breathing in air to the lungs.

Inspiratory Capacity (IC)
The maximum amount of air that can be breathed in at the end of a normal quiet expiration.

Inspiratory Reserve Volume (IRV)
Inspiratory reserve volume is the maximal amount of air that can be breathed in with the most effort after a normal (quiet) inspiration.

How hard and how many of each type of activity to do. Intensity can be measured using Rating Perceived Exertion Scale.

Intercostal Muscles
These muscles are located between the ribs. They contract during inspiration and expand the rib cage to help with breathing.

The part of the lung that includes a portion of the connective tissue of the blood vessels and air sacs and makes up the membrane where gas exchange (oxygen and carbon dioxide) takes place in the lung.

Intravenous (IV)
Into the vein.

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Job's Syndrome
A disorder of neutrophils characterized by the presence of abnormal or absent chemotactic responses and hyperimmunoglobulinemia E. It is transmitted as an autosomal recessive trait and most cases reported have been in girls.


Kartagener's Syndrome
An inherited disorder involving a combination of situs inversus, bronchiectasis, and sinusitis.

A condition characterized by high levels of nonconjugated bilirubin in the blood with biliary pigmentation of certain nuclei in the brain and spinal cord. Frequently results in cerebral palsy, mental retardation, and hearing deficit. It is commonly a sequel to icterus gravis neonatorum.

Kartagener's Syndrome


Killer Cells
Lymphocyte-like effector cells which mediate antibody-dependent cell cytotoxicity. They kill antibody-coated target cells which they bind with their Fc receptors.

Killer Cells, Lymphokine-Activated
Cytolytic lymphocytes with the unique capacity of killing natural killer (NK)-resistant fresh tumor cells. They are interleukin-2-activated NK cells that have no MHC (major histocompatibility complex) restriction or need for antigen stimulation. LAK cells are used for adoptive immunotherapy in cancer patients.

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Killer Cells, Natural
Cells responsible for spontaneous cytotoxicity of a variety of tumor cells without prior immunization. These natural killer cells are found in non-immune humans and experimental animals and are thought by some to be the same as KILLER CELLS (killing by antibody-dependent cell cytotoxicity), but they can also kill in the absence of antibody.

Kupffer Cells
Large star-shaped or pyramidal cells with a large oval nucleus and a small prominent nucleolus. These intensely phagocytic cells line the walls of the sinusoids of the liver and form a part of the reticuloendothelial system. (Dorland, 27th ed)


Lambert-Eaton Myasthenic Syndrome
An acquired autoimmune disease characterized by weakness and fatigability of proximal muscles, particularly of the pelvic girdle and thighs, with relative sparing of extraocular and bulbar muscles. It is often associated with small cell carcinoma of the lung.

Langerhans Cells
Recirculating, dendritic, antigen-presenting cells containing characteristic racket-shaped granules (Birbeck granules). They are found principally in the stratum spinosum of the epidermis and are rich in Class II major histocompatibility complex molecules.

Laryngeal Cartilages
The nine cartilages of the larynx, including the cricoid, thyroid, and epiglottic, and two each of arytenoid, corniculate, and cuneiform.

Laryngeal Diseases
Disorders of the larynx, general or unspecified.

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Laryngeal Edema
Edema of any region of the larynx from a variety of causes. In the earliest stages it may be difficult to differentiate from infection, although mucosal injection and erythema are found more often in the latter. Allergic edema may result as a response from provocation induced by foods, inhalants, and drugs. The entire respiratory tract or only an isolated portion of the larynx may be affected. Laryngeal edema may also be hereditary. Other possible causes of laryngeal edema include increased capillary pressure due to superior vena cava syndrome, intemal jugular vein ligation, lowered plasma osmotic failure induced by renal failure, impaired lymphatic flow, and increased capillary permeability to proteins. (From Paparella et al., Otolaryngology, 3d ed, p2253)

Laryngeal Mucosa
The mucous lining of the larynx; mainly stratified squamous epithelium in the upper part and ciliated columnar in the lower part of the larynx.

Laryngeal Muscles
The intrinsic muscles of the larynx are the aryepiglottic(us), arytenoid(eus), cricoarytenoid(eus), cricothyroid (eus), thyroarytenoid(eus), thyroepiglottic(us), and vocal(is).

Laryngeal Neoplasms
Cancers or tumors of the larynx or any of its parts: the glottis, epiglottis, laryngeal cartilages, laryngeal muscles, and vocal cords.

Spasm of the larynx.

Inflammation of the larynx. This condition presents itself with dryness and soreness of the throat, difficulty in swallowing, cough, and hoarseness.

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Stricture or narrowing of the larynx. This condition may be developmental or acquired, with progressive respiratory difficulty as a symptom.

An irregularly shaped, musculocartilaginous tubular structure lined with mucous membrane, located at the top of the trachea and below the root of the tongue and the hyoid bone. It is the essential sphincter guarding the entrance into the trachea and functioning secondarily as the organ of voice.

Laser Bronchoscopy
A very powerful and precise tool to destroy tumor occluding the airways and to control bleeding in the airways.

Latex Allergy
Hypersensitivity to products containing processed natural rubber latex such as rubber gloves, condoms, catheters, dental dams, balloons, and sporting equipment. Both T-cell mediated (delayed hypersensitivity) and IgE antibody-mediated (immediate hypersensitivity) allergic responses are possible. Delayed hypersensitivity results from exposure to antioxidants present in the rubber; immediate hypersensitivity results from exposure to a latex protein.

Infections with bacteria of the genus Legionella

Legionnaires' Disease

Leukemia, Hairy Cell
A neoplastic disease of the Iymphoreticular cells which is considered to be a rare type of chronic leukemia; it is characterized by an insidious onset, splenomegaly, anemia, granulocytopenia, thrombocytopenia, little or no lymphadenopathy, and the presence of "hairy" or "flagellated" cells in the blood and bone marrow.

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Leukemia, Lymphocytic
Leukemia associated with hyperplasia and overactivity of the lymphoid tissue. There are increased numbers of circulating malignant lymphocytes and Iymphoblasts. (Dorland, 28th ed, p919)

Leukemia, Myelocytic, Acute
Progressive, malignant disease of the myeloid tissue in which the granular, polymorphonuclear leukocytes and their precursors predominate.

Leukemia, Myeloid
Form of leukemia characterized by an uncontrolled proliferation of the myeloid lineage and their precursors in the bone marrow and other sites.

Leukemia, Nonlymphocytic, Acute
Acute leukemia distinguished from acute lymphocytic leukemia (ALL) by the morphology of the marrow and blood leukemic cells. Cytoplasmic granules are usually present and the nucleus is usually large and irregular. ANLL is more common in adults than ALL and occurs at any age.

Leukocyte-Adhesion Deficiency Syndrome
Rare, autosomal recessive disorder caused by deficiency of the beta 2 integrin receptors comprising the CD11/CD18 family of glycoproteins. The syndrome is characterized by abnormal adhesion-dependent functions, especially defective tissue emigration of neutrophils, leading to recurrent infection.


Leukocytes, Mononuclear

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Likelihood of Overall Survival
The likelihood that people with COPO survived all causes of death, including COPO, at a specific point in time. This probability is reported as a percentage.

An organ in the abdomen that contains phagocytes and helps make complement.


Lung Abscess
A complication of a localized area of pneumonia or when a neoplasm becomes necrotic and contains purulent material that cannot drain easily from the area because of partial or complete bronchial obstruction (Harrison's Principles of Internal Medicine, 12th ed, p1068)

Lung Diseases
Disorders of the lung, general or unspecified.

Lung Diseases, Fungal
Disorders of the lung, caused by fungi

Lung Diseases, Interstitial
A heterogeneous group of noninfectious, nonmalignant disorders of the lower respiratory tract, affecting primarily the alveolar wall structures but also often involving the small airways and blood vessels of the lung parenchyma. "Interstitial" refers to the fact that the interstitium of the alveolar walls is thickened, usually by fibrosis. This group of diseases is usually inflammatory. (Dorland, 27th ed; Wyngarden, Cecil Textbook of Medicine, 19th ed, p396)

Lung Diseases, Obstructive
Any disorder marked by persistent obstruction of bronchial air flow.

Lung Diseases, Parasitic
Infections of the lungs with a parasite. They are caused most commonly by nematodes (roundworms).

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Lung Neoplasms
Neoplasms or tumors of the lung tissue.

Lung, Hyperlucent
Hyperlucency of one lung with decreased size and vascularity of the lung. It is often associated with BRONCHIOLITIS OBLITERANS and with adenovirus infection in childhood.

Lung volume -The total amount (volume) of gas in the lungs is subdivided into compartments. Tidal volume (VT or TV) is the volume of air that enters the lungs during inspiration and leaves the lungs during expiration. Functional residual capacity (FRC) is the volume of air that remains in the lungs at the end of a normal expiration. Total lung capacity (TLC) is the volume of air in the lungs after a maximal inspiration. Vital Capacity (VC) is the maximum volume of air that can be exhaled form the lungs after a maximum inspiration Residual volume (RV) is the volume of air remaining in the lungs after a maximum expiration.

Lung Volume Reduction Surgery (LVRS)
The surgery that is performed on patients with emphysema to reduce that amount of lung in the chest cavity.

Lupus Erythematosus, Systemic

Lupus Nephritis
Glomerulonephritis associated with systemic lupus Erythematosus. It is classified into four histologic types: mesangial, focal, diffuse, and membranous.

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A transparent, slightly yellow liquid of alkaline reaction, found in Iympahtic vessels and derived from the tissue fluids. Lymph is collected from all parts of the body and returned to the blood via the lymphatic system. (Dorland, 28th ed)

Lymph Nodes
Any of the accumulations of lymphoid tissue organized as definite lymphoid organs, varying from one to 25 mm in diameter, situated along the course of lymphatic vessels. The lymph nodes are the main source of lymphocytes of the peripheral blood and, as part of the reticuloendothelial system, serve as a defense mechanism by removing noxious agents, such as bacteria and toxins, and probably playa role in antibody production. (Dorland, 28th ed)

A tumor-like condition characterized by smooth muscle and endothelium proliferation of lymphatic vessels and lymph nodes in the mediastinum and retroperitoneum, also in the lung. It may be manifested by chylous pleural effusion and ascites.

A progressive disorder of women of child-bearing age, marked by nodular and diffuse interstitial proliferation of smooth muscle in the lungs, lymph nodes, and thoracic duct. (Dorland, 27th ed)

Lymphatic System
The lymphatic vessels and lymphoid tissue, considered collectively. (Dorland, 28th ed)

Lymphocyte Subsets
A classification of lymphocytes based on structurally or functionally different populations of cells.

White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each); those with characteristics of neither major class are called null cells.

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Lymphocytes, Null
A class of lymphocytes characterized by the lack of surface markers specific for either T or B lymphocytes.

Lymphocytes, Tumor-Infiltrating
Lymphocytes that show specificity for autologous tumor cells. Ex vivo isolation and culturing of TIL with interleukin-2, followed by reinfusion into the patient, is one form of adoptive immunotherapy of cancer.

Lymphoid Tissue
A lattice work of reticular tissue the interspaces of which contain lymphocytes; lymphoid tissue may be diffuse, or densely aggregated as in lymph nodules and nodes. (Dorland, 28th ed)

Reduction in the number of lymphocytes.

Lymphoproliferative Disorders
Disorders characterized by proliferation of lymphoid tissue, general or unspecified.

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