| 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. (12 Dec 1998) |
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| killer cells, lymphokine-activated | Cytolytic lymphocytes with the unique capacity of killing natural killer (nk)-resistant fresh tumour 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. (12 Dec 1998) |
| killer cells, natural | Cells responsible for spontaneous cytotoxicity of a variety of tumour 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. (12 Dec 1998) |
| killer plasmid | <molecular biology> These plasmids are found in some strains of Kluyveromyces marxianus where the cells contain multiple cytoplasmic copies of dsDNA plasmids. Such cells secrete a glycoprotein toxin. The plasmids and the killer function can be transferred to yeast. (18 Nov 1997) |
| killer T-cell | 1. <immunology> Mammalian cells which can lyse antibody coated target cells. They have a receptor for the Fc portion of IgG and are probably of the mononuclear phagocyte lineage, though some may be lymphocytes. Not to be confused with cytotoxic T-cells which recognise targets by other means and are clearly a sub set of T lymphocytes. This confusion exists in the early literature. 2. Natural killer cell are CD3 negative large granular lymphocytes, mediating cytolytic reactions that do not require expression of Class I or II major histocompatibility antigens on the target cell. 3. Lymphokine activated killer cells are NK cells activated by interleukin-2 (LAK cells). (13 Nov 1997) |
| killer yeast | <microbiology> A yeast that secretes a toxin that can kill other yeasts. (09 Oct 1997) |
| Killian's bundle | Origin, outer surfaces of thyroid (thyropharyngeal part) and cricoid (cricopharyngeal part, musculus cricopharyngeus; superior or upper oesophageal sphincter muscle) cartilages; insertion, pharyngeal raphe in the posterior portion of wall of pharynx; action, narrows lower part of pharynx in swallowing, the cricopharyngeal part has a sphincteric function for the oesophagus, allowing some voluntary control of eructation and reflux; nerve supply, pharyngeal plexus. Synonym: musculus constrictor pharyngis inferior, cricopharyngeus muscle, laryngopharyngeus, musculus laryngopharyngeus. (05 Mar 2000) |
| Killian's operation | <procedure, surgery> An operation for frontal sinus disease in which the entire anterior wall is removed and the mucous membrane is curetted away. The ethmoid cells are scraped out through an opening in the nasal process of the maxillary bone, and the upper wall of the orbit is removed as well. (05 Mar 2000) |
| Killian's triangle | <anatomy> The triangular-shaped area of the cervical oesophagus bordered by the oblique fibres of the inferior constrictor muscle of the pharynx and the transverse fibres of the cricopharyngeus muscle through which Zenker's diverticulum occurs, and the A-V nodal triangle between the coronary sinus orifice and the ventricular crest. Synonym: laimer triangle. (05 Mar 2000) |
| Killian, Gustav | <person> German laryngologist, 1860-1921. See: Killian's bundle, Killian's operation, Killian's triangle. (05 Mar 2000) |
| killifish | <marine biology> Any one of several small American cyprinodont fishes of the genus Fundulus and allied genera. They live equally well in fresh and brackish water, or even in the sea. They are usually striped or barred with black. Synonym: minnow, and brook fish. Source: Websters Dictionary (21 Jun 2000) |
| killigrew | <zoology> The Cornish chough. Source: Websters Dictionary (01 Mar 1998) |
| killock | A small anchor; also, a kind of anchor formed by a stone inclosed by pieces of wood fastened together. Alternative forms: killick. Source: Websters Dictionary (01 Mar 1998) |
| kilo | <prefix> A prefix used in the SI and metric systems to signify 1000 times the following unit. For example, a kiloampere is 1000 amperes. Origin: French fr. G. Chilioi, one thousand (05 Mar 2000) |
| kilobase | <molecular biology, unit> Unit of length for DNA fragments equal to 1000 nucleotides. Abbreviation: kb (09 Oct 1997) |