What is Cells: Definition and 450 Discussions

A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be easily distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface.
T cells are born from hematopoietic stem cells, found in the bone marrow. Then, developing T cells migrate to the thymus gland to mature. T cells derive their name from this organ where they develop (or mature). After migration to the thymus, the precursor cells mature into several distinct types of T cells. T cell differentiation also continues after they have left the thymus. Groups of specific, differentiated T cell subtypes have a variety of important functions in controlling and shaping the immune response.
One of these functions is immune-mediated cell death, and it is carried out by two major subtypes: CD8+ "killer" and CD4+ "helper" T cells. (These are named for the presence of the cell surface proteins CD8 or CD4.) CD8+ T cells, also known as "killer T cells", are cytotoxic – this means that they are able to directly kill virus-infected cells, as well as cancer cells. CD8+ T cells are also able to use small signaling proteins, known as cytokines, to recruit other types of cells when mounting an immune response. A different population of T cells, the CD4+ T cells, function as "helper cells". Unlike CD8+ killer T cells, these CD4+ helper T cells function by indirectly killing cells identified as foreign: they determine if and how other parts of the immune system respond to a specific, perceived threat. Helper T cells also use cytokine signaling to influence regulatory B cells directly, and other cell populations indirectly.
Regulatory T cells are yet another distinct population of T cells that provide the critical mechanism of tolerance, whereby immune cells are able to distinguish invading cells from "self". This prevents immune cells from inappropriately reacting against ones' own cells, known as an "autoimmune" response. For this reason, these regulatory T cells have also been called "suppressor" T cells. These same regulatory T cells can also be co-opted by cancer cells to prevent the recognition of, and an immune response against, tumor cells.

View More On Wikipedia.org
Recent contents Top users
  1. P

    Calculating Charge Flows in Chemical Cells: How Much Zinc Reacts per Second?

    Hi there! Could anyone help me out with this question? Which steps should I take in solving this question? Chemical cells can produce quite large charge flows for substantial times before their chemicals have all reacted. If zinc is the metal losing electrons under chemical attack, what mass...
  2. Holocene

    Sex Cell Variation: Do Sperm Cells Differ?

    Sex cell? Quick question: Does every sperm cell in a male testicle contain the same genes, or can some sperm cells contain different genes, even though they are from the same person?
  3. D

    Hydrogen Fuel Cells: Challenges and Benefits - django

    Hi! I'm django, new member. Right, I would like to talk about fuel cells. At first glance they are great, right! 99% fuel efficieny. But what most peopkle don't realize, is that although hydrogen might well be the most predominant element in the Universe, it is not available on Earth in...
  4. D

    Electrolytic vs. electrochemical vs. galvanic cells.

    So my question is what is the difference between these cells? This always confuses me. I know that electrolytic cells are nonspontaneous and that their cathode is negative which means that electrons are going against their gradients here. I am also aware of the fact that a galvanic cells is...
  5. Y

    Calculate the probability for 2 different digits in 4 cells.

    The set S={1,2,3,4}, there are 4 cells. What is the probability for 2 different digits (from S) to appear in 4 cells? Example: 1,1,1,2 =>good 3,4,4,3 =>good 2,4,2,2 =>good 1,2,3,4 =>not good 1,2,3,3 =>not good 1,1,1,1=>not good
  6. L

    Questions on electrochemical cells using Zn, Cu

    The problem http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/animations/CuZncell.html After veiwing the animation found at the website above answer these questions: Is there an electron transfer between species? Which species is losing electrons Which species...
  7. F

    Standard Reduction Potentials of 1/2 Cells

    Homework Statement Use half-reactions and E's to determine the result of storing a solution of CuSO4 in a tin container. Homework Equations [Table of Standard Reduction Potentials of Half-Cells] The Attempt at a Solution My question isn't exactly how to do this question. I was just...
  8. M

    Anions in Galvanic Cells: Attraction & Dissolution

    In a galvanic cell is it the anions from the electrolyte which is attracted to the cathode or is it the anions produced from the anode dissolving which flow to the cathode?? Also it mentions that the charges increase in energy as they pass through the power supply and they decrease when they...
  9. E

    Where to Buy Peltier Cells Online - Get Help Now!

    Hi everyone I need to know where can I buy Peltier cells in internet. can someone help me? Thank in advance
  10. F

    Solar Cells - Is there anyone here involved in research, production, hobby, etc

    I have an upcoming paper to write for my solar cells course. The question is something along the lines of, if we have a p-n junction which side should we shine the light on for efficiency? Should it shine on the p side or the n side? Efficiency at this point is defined loosely, and can range...
  11. L

    What Reactions Occur in a Battery with Two Half Cells?

    Homework Statement I have got a battery with two half cells. One cell with. A silver rod in a 100 mL AgNO3 0,025 M solution. One cell with. A zinc rod in a 100 mL Zn(NO3)2 0,150 M solution. So my question is what reactions happen? And which reaction is the electricity providing...
  12. A

    Advice for one who wishes to design solar cells

    I am thinking I should study electrical engineering as well as materials engineering up to a bachelor level; is this a wise plan if I hope to design solar cells. Also, how easily could I collaborate with others to do research in order to gain connections to get such a job, or at least related...
  13. Q_Goest

    What are some examples of genes being active in Slug cells?

    In a http://www.sciam.com/article.cfm?chanID=sa003&articleID=CF2AA0B2-E7F2-99DF-34CD01DE3E68F8ED&ref=rss", it says: What do they mean when they say 10,000 genes "could be active"? What are these genes doing in the brain cell which is interpreted as 'being active'?
  14. D

    Please answer this one quick question (about fuel cells)

    I'm a physics student trying to do a project on fuels cells. One thing I don't get is, when the atom goes through the electr-- whatever, how does it separate into electrons and protons. I thought the only way to separate electrons from the nucleus is by extreme heat and pressure, like that...
  15. B

    How long do nutrients stay in cells?

    Nutrients in cells question?? This question may again be too technical but does anyone now how long nutrients used for 'fuel' remain in cells (when they're not being stored - I believe they're only stored in muscle, fat and liver tissue)? For example, if a glucose molecule enters a cell from...
  16. F

    Do male or female reproductive cells age ?

    When spermatogonia divide by mitosis, do there telomeres shorten ? I am just trying to ask if reproductive cells age as well as with the rest of our bodies cells ? If so wouldn't a baby born from old parents have a shorter than average life expectancy due to older or more aged DNA ?
  17. C

    How Do Virus Coat Protein Genes Make Plant Cells Resistant to Viruses?

    My Bio textbook says that, by introducing the virus coat protein gene into a plant cell the cell becomes virus resistant. How is that possible?
  18. K

    Forming Structures from Cells: Exploring Bone Cell Replication

    I've only taken high school biology and I'm actually a computer science major, but I've had an idea rolling around in my head recently and I think it might be better realized if I approach the problem from a biological standpoint. I'm sort of stuck at a particular problem that I can't seem to...
  19. W

    All New Cells Every Seven (Nine?) Years?

    Greetings! I have read/heard from various sources that none of the cells in my (or any other human's) body now are the same as they were seven (At least one source said nine years) years ago. I remember reading from one source that some cells don't "die" but all of the separate parts are...
  20. B

    Biology Help: Sperm & Egg Cells, Genes & Their Functions

    Biology Help ! Female cimpanzees often mate with more than one male. The different males' sperm cells race each other to reach the egg first. Both Modja and Tatu have mated with Tanu in the last hour. a) In which part of a sperm cell and an egg cell are the genes found? b) What do genes...
  21. T

    Diamond anvil cells and maximum pressure

    I was checking out diamond anvil cells and i have few questions. I have been on this sites: http://www.physlink.com/Education/askExperts/ae483.cfm (1) http://www.matweb.com/search/SpecificMaterial.asp?bassnum=CDiamA (2) http://merkel.zoneo.net/FEM/index.php?lang=en (3) 1.what is max...
  22. zoobyshoe

    Medical Does Alcohol Really Kill Brain Cells?

    There's a common belief that every glass of alcohol you drink kills a certain number of brain cells. This is a myth I thought I'd clear up here, one that results from a severe condition sometimes seen in chronic alcoholics called Wernicke-Korsakov's Syndrome...
  23. G

    Explaining Opposite Ionic Flow in Galvanic & Electrolytic Cells

    My chem teacher is having trouble explaining the a particular happening in a fuel cell to the class. In a galvanic cell +ve ions move towards the +ve electrode and -ve to the -ve. In electrolytic cells the +ve ions move towards the -ve electrode and -ve to the +ve. He says that the reason why it...
  24. M

    Alternative ideas for stem cells.

    Now I'm sure everyone has heard of George w. Bush's veto of the stem cell bill; because killing stem cells is like killing people, even though Bush is pro-death penalty. MY thought. Is it plausable to have a drug, radiation, or whatever. Which stops the meiosis transformation of the diploid...
  25. D

    Solutions for High Temperature Fuel Cells

    Hey everyone, I found this really interesting article on Technology Review about a new technology that could remove the sulpur from high-temperature fuel cells. The sulpur causes the eventual shut down of these fuel cells, but with this new technology the cells continue working and are...
  26. P

    Exploring Hydrogen Fuel Cells for Energy

    i was thinking over how a hydrogen fuel cell works, seperating the electrons and protons (into its ions like any other way of converting electrical energy to chemical) but i wondered if the protons as well as the electrons could be used as a current to creat a circuit such as the electrons do...
  27. Pengwuino

    Zinc-air fuel cells, advantes/disadvantages?

    So my uncle approaches me today with some investor guide dealy. It takes albout some Power Airtech company and how it is going to introduce some zinc-air fuel cell that they developed with LLNL. Can someone explain the advantages and disadvantages of such a system. They made it out to be greater...
  28. W

    Binomial distribution - killing cells with x-rays

    Dear Fellow mathematicians and Physicists,I am doing some MC modelling on tumour growth and radiotherapy treatment modelling and would like to know: Who out there would agree (or suggest alternatives) to the theroy that the chance of a cell being damaged/hit with radiation (and therefore...
  29. L

    What are the conditions for a voltmeter reading of 0 in an electrochemical cell?

    i need help on writing redox reactions and with finding the electrode in oxidization and in reduction. oh and what are the three conditions under which the voltmeter reading will be 0 (zero)? THANKS:biggrin:
  30. B

    Exploring the Unfulfilled Promise of Fuel Cells

    About an year ago, i had heard a lot about the upcoming technology of fuel cells. i was pretty intrigued by the description that it combined, hydrogen and oxygen to form pure water. no wastage. i believed it would be the alternative fuel we were in search of. why then is there not much...
  31. W

    Putting chloroplasts into animal cells?

    have anyone of you ever thought of putting chloroplasts into animal cells? What would happen if i did?
  32. D

    Fuel Cells that Run off Ethanol or Sugar Possible?

    Is it possible to make fuel cells that run of ethanol or even sugar? :confused: Is it a good idea? Why/Why not?
  33. S

    An 'ethical' way to get stem cells

    :uhh: Atleast no one gets hurt(I think..)...Lets hope there's more research on stms cells.
  34. Hootenanny

    Scatter Plot in Excel - Referencing Cells Merged or Not

    I am trying to do a scatter plot in Excel, and I am referencing points from a different sheet. However, excel won't let me reference more than eight cells. Some of the cells are merged, I don't know if that will affect it... Any help would be appreciated.
  35. P

    Are Egg Shells and Crab Shells Made Up of Cells?

    The textbook says that every living thing is made up of cells. What about the shell of a crab or egg shells? Are they inert matter or made up of cells? If they are made out of inert matter than how does the organism control their function?
  36. C

    Mitosis at Telophase: Decreasing Cells

    decreases during the stage of mitosis...at which point specifically? Telophase?:grumpy:
  37. iansmith

    Dendritic cells and mouse cycle

    Lately in our lab, the DC have been growing more rapidly than usual (4 days vs 6 days). Our lab is new to cell culture but according another lab in our department has the same problem. It appears that the problem is seasonal and it start in early in the fall and ends around christmas. Does...
  38. Ivan Seeking

    Medical Are Mice with Human Brain Cells Ethically Acceptable?

    http://pittsburghlive.com/x/tribune-review/health/s_403491.html
  39. S

    Materials manufactured by cells

    Can anyone list some substances other than penicillian and insulin that are produced by organizms. It seems like most complex molocuels are produced by everything but chemical engineers. Am I correct in thinking that this is because it is very difficult to produce specific complex molocuels on a...
  40. G

    Minerals vs Cells: Comparing Composition & Structure

    what is the difference between a mineral and a cell? is a mineral made out of cells? what is the chemical composition of a mineral as opposed to a cell (preferably the simplest cell, a unicellar organism)??
  41. S

    Turbulent Cells and Telescopes: Seeking Help

    I don't understand why these turbulent cells in the atmosphere tend to cause different problems in larger and smaller scale telescopes. anyone who can help me out?
  42. D

    Highlighting Cells with IF - A Step-by-Step Guide

    Hello, can you tell me hjow to highlight a cell with IF ? eg IF(A1>100,HIGHLIGHT,NotHIGHLIGHT) <<<<<< somethin like that ? Thank you :smile:
  43. J

    OT- animations of cells doing what they do

    noob, :) just wondering if anyone knows of any sites (links) that show animations of any types of cells doing what they do. thanks jimmie
  44. cronxeh

    Exploring the Chemistry of Stem Cells

    As I'm watching the PBS presentation about stem cells ( http://www.pbs.org/wgbh/nova/sciencenow/3209/04.html ) and the debate on whether we should use the stem cells for research or not, I wonder what is the chemical make up of those stem cells. It is obvious that it is a DNA molecule, so it is...
  45. P

    Total Current Increase when Cells Connected in Parallel

    When the cells are connected in parallel, what happens to the total current drawn when compared with the arrangement that the cells are connected in series?
  46. C

    Making cells build nano-machines

    Is it possible to make microorganism create nano-objects or nano-machines? Any known experiment? Regards!
  47. P

    How Can a Mathematical Formula be Set Up for Tumor Cell Growth?

    If a tumor cell grows with rate m, and dies with rate n (m>n), their population number is P, after tme t, how can set up a mathematical fomuler for growth ? If i also have data from 100 patients, is it useful ? Thanks
  48. P

    Help Save a Patient's Life: Calculating Infected Cells

    A patient caught an influenza for example and the virus is killing him. In his blood, there are fights against the virus and let say, one infected cell can infect also other neighboring cells. Do you know what and how can I set up a rule to calculate the numbers of healthy cells after 't time'...
  49. D

    Advantages & Disadvantages of Connecting Cells in Parallel

    Well yesterday it was my physics paper(o'levels) . There was a question there which asked what is the advantage of having cells connected in parallel combination? I wrote that By connecting the cells in parallel combination the total current in the circut is shared by all of the cells as a...
  50. C

    Do All Antigen-Presenting Cells Migrate to Lymph Nodes?

    Antigen-presenting cells... When antigen-presenting cells (eg - macrophages, dendritics, etc) encounter antigens, do they all migrate to the lymph nodes? What causes them to do this? I know from sources I've read that dendrites do it, but do macrophages as well - or does the macrophage...
Back
Top