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    4 days ago

    Wow, I had no idea. Thank you.

    Is macrophage just a term I hadn’t come across for virus fighting cells that we make, or am I right to be surprised that we have them? (I heard of their existence, but didn’t realise they are made by creatures rather than just evolving separately.)

    Do mumps and rubella work in any kind of a similarly unusual way, or is it just coincidence that we need those three at around the same age?

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      4 days ago

      Macrophage is just another name for the “common” white blood cell. They are the cells that eat up bacteria and viruses, and are part of the general immune system. The general immune system can deal with the everyday stuff - the pathogens you are exposed to every day, for example low levels of bacteria, but they also are involved in cleaning up the remnants of dead cells. they engulf their targets and break them down (for example using H2O2). If they can’t keep up, they summon additional help, and part of that is that white blood cells travel to the lymph nodes and there present fragments of the intruder on their surface. (nearly all cell types present fragments of what they break down on their surface, but normally those are only their own stuff, which is ignored by the immune system)

      The immune cells then start producing antibodies - at random, until one of the antibodies sticks to the fragment presented. The cell that produced this successful antibody then continues to make more of them - the antibodies themselves are like “little flags” that mark targets. Like i said before, nearly all cells present parts of what they have inside of them to the outside - the flood of antibodies is now able to mark all infected cells in case of a virus infection, or mark bacteria. After the infection subsides, the cells that produced antibodies becomes dormant - it is now a memory cell, which can be rapidly reactivated if the same pathogen shows up again, you are now immune.

      Measles don’t get broken down in macrophages - their capsule is adapted to that process. instead of getting broken down, the virus infects the cell, which still wants to show that it caught something. in the lymph nodes the virus breaks the macrophage open, infecting the immune cells that are amassed there, and this includes the memory cells. After a while the immune system becomes able to kill off the measles, but by that time the damage is done and your immune systems memory is wiped out.

      Mumps and Rubella work differently - that those are in one vaccine has more to do with that the three vaccines don’t interfere with each other, and that the immunity imparted by the mother wears off around that time and the child’s immune system takes over, enabling a immune response.

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        3 days ago

        Superbly informative, thank you.

        I heard once that some scientist was collecting phages in the sewer outside a hospital in the hope that they might find help for people with antibiotic resistant bacteria. Are such phages similar, different or the same as white blood cells?

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          3 days ago

          Those are completely different things - bacteriophages are bacteria specific viruses that, like bacteria, occur pretty much everywhere. There are more bacteriophages than there are other lifeforms on this planet combined. Good thinking of that scientists tho - phages that can kill off MRSA would love hospital sewers.