Immune system
kbonham | June 9, 2011In the wild, as I wrote about last week, some strains of commensal bacteria in mosquitoes seem to confer some resistance to infection with Plasmodium, the parasite that causes malaria in humans. Not content to wait for for nature to get around to it, researchers at Johns Hopkins University decided to see if they could nudge the process along:
Wolbachia Infections Are Virulent and Inhibit the Human Malaria Parasite Plasmodium Falciparum in Anopheles Gambiae
Wolbachia is a type of bacterium that often infects insects, including mosquitoes, and causes incredibly strong immune responses, but no…
kbonham | May 9, 2011Way back in high school bio, I learned about the 2 main ways that eukaryotic organisms (everything other than bacteria and archaea) make their metabolic living: photosynthesis and oxidative phosphorylation (also known as respiration). These two processes are fundamentally related - photosynthesis combines CO2 and water to produce sugar and oxygen, while respiration breaks down sugars using oxygen, leaving water and CO2. But the cells of plants, animals and fungi can't do either of these things on their own. Sometime in our distant evolutionary past, we took on tiny passengers that do the work…
kbonham | May 3, 2011[A while back, I received a question from a reader via e-mail.
Dear Beasties:
If you had a mutation in either C4 or C5 which one would be worse... I guess the question is is it more important to have the ability to opsonize or the ability to lyse cells with the MAC complex?
I could have done some digging and given a perfunctory answer, but I decided instead to ask my friend Matt Woodruff, another 3rd year grad student in my program whose lab works on compliment, if he could provide an answer and a bit of background. I think you'll agree it was the right choice.
The Compliment System
by Matt…
kbonham | May 1, 2011Last year, I was awarded an NSF graduate research fellowship. This fellowship pays my tuition and stipend for 3 years, so that my boss doesn't have to. This is a great help to our lab, though I don't really get much in the way of direct benefit* (other than a great line on my CV). Anyway, every year, we are required to submit an "activities report" that says what we've been doing with the money, which in the end is your money (if you pay taxes in the US that is). It's supposed to be written for a general audience, and since you all are paying for me to do the science that I love, I figured…
kbonham | March 26, 2011Our immune system needs to be on a hair-trigger. When you breathe in a virus or a bacterium enters a cut on your arm, you don't want to mess around:
(disclaimer: most of what George Carlin says in the rest of that clip is not supported by the science (though it's funny as hell))
But all of that heavy immunological artillery is dangerous, and when it's directed at the wrong target, there can be a lot of collateral damage. Some of the most important parts of the immune system are mechanisms of tolerance - teaching the immune system to ignore the things that aren't a threat. For the innate…
kbonham | February 23, 2011If you were going to design the perfect immune system, what would you do? This question is often posed to beginning immunology students, and the best answer may be so obvious that it doesn't occur to most. The best immune system is one that prevent pathogens from ever gaining access to your squishy bits in the first place.
And so we have barriers - lots of them. Unfortunately, the best barriers are not always practical. Plants have rigid cell walls that are almost impervious to pathogens, but plants don't need to walk around. We trade that in for skin and that does pretty well, but it has…
kbonham | December 26, 2010As Boston gets buried under a layer of snow (wooo! blizzard!), the the Weekend Review makes a return with one of my favorite topics: gut microbes.
The fields of immunology, microbiology, nutrition and metabolism are rapidly converging. Here we expand on a diet-microbiota model as the basis for the greater incidence of asthma and autoimmunity in developed countries.
Two important advances in the fields of immunology and gut microbiology have emerged in recent years. First, it has been clearly demonstrated that diet has a considerable effect on the composition of the gut microbiota. Different…
kbonham | November 30, 2010Cancer sucks. I'm sure I don't have to tell you that - it's one of the leading causes of death in developed countries, and our treatment options are pretty thin. Basically, it amounts to cutting out the tumors that can be seen, and then giving a controlled administration of poison in the hopes that the cancer cells die before you do. Don't get me wrong - advances in oncology have saved many lives, but it's no surprise that there's a lot of research happening to find better options.
One promising avenue of study is augmenting the immune system to fight cancer directly. It's known that the…
kbonham | November 28, 2010If you've ever rolled your ankle (as I have many times), you have a visceral knowledge of inflammation. Clinically, inflammation is the redness, swelling, heat and pain that's associated with injury. From an immunologist's perspective, it's the set of molecular events that get the immune system going. All of the clinical systems associated with inflammation are due to increased vascular permeability, which is just a fancy way of saying leaky blood vessels. Actually, "leaky" implies that it's uncontrolled, when in fact there's a very orchestrated set of events that recruit immune cells and…
kbonham | November 22, 2010Most of my favorite long-standing discussions with friends and family tend to resolve around definitions. My good friend Paul and I have had hours upon hours of discussion about the nature of the universe - he calls his perception of the order of the universe "god," and I call myself an atheist (interestingly, that picture was taken by Paul), though in practical terms I don't think our beliefs are really that far apart. He says his definition allows him to engage with religious people, I say it just causes confusion.
In my first year of graduate school, I used to argue endlessly with my class…
kbonham | November 13, 2010Last week, I talked about strategies to improve vaccine efficacy and safety. Most of those strategies were in the context of standard, inject-into-your-arm vaccines, but what about totally new delivery methods? This week, there was a review in PLoS Pathogens of strategies for generating vaccines that you can swallow:
Enhancing Oral Vaccine Potency by Targeting Intestinal M Cells
The immune system in the gastrointestinal tract plays a crucial role in the control of infection, as it constitutes the first line of defense against mucosal pathogens. The attractive features of oral immunization…
kbonham | November 12, 2010Macrophages are really good at gobbling stuff up. It's all right there in the name - they are big (macro) eaters (phage). I study them in the context of the immune system - one of the things they do really well is eat up bacteria and other pathogens that have found their way into your tissues. As a front line sentinel, they also are capable of kick-starting inflammation and recruiting the rest of the cells necessary to clear an infection. But that's not all, there's more.
Weight loss and lipolysis promote a dynamic immune response in murine adipose tissue
Here we characterized the response of…
kbonham | November 6, 2010I have a love/hate relationship with Nature Reviews: Immunology. It comes out once per month, and is usually packed with easy to read articles about fascinating (to me) topics, and each is filled with tons of great references so I can dig into the issue more. On the one hand, I get really excited about all the great things to read and new ways to expand my knowledge. On the other hand - that's a lot of reading. My Instapaper queue is about 80% Nature Reviews (15% other papers, and 5% random crap).
This month is no different, but I decided to have the goal of blogging about the ones that I…
kbonham | November 5, 2010Most biological systems have trade-offs, so this really shouldn't come as a surprise. A recent paper published in Science shows that in sheep, some females have a stronger immune system and tend to live longer, but also tend to reproduce less often. This seemed to translate to roughly equal reproductive fitness over the course of their lives. It's a cool study, clearly involving a lot of work (they took samples over the course of a decade). The New York Times comes soooo close to having a great science article - they just forgot one thing.
They found that the average life span of the 410 ewes…
kbonham | November 4, 2010I started writing this post before I read ERV dissecting some "the immune system is perfect" BS. Go read hers, then come back if you want more.
Now that I've gone through the basics of a typical immune response, I think it's necessary to point out some of its many flaws. In many of the immunology courses I've taken, the mammalian immune system is presented almost as the pinnacle of evolution, but it is far from perfect. In fact, in many ways, we might be better off if it had never evolved at all.
First up - Autoimmunity. T-cells and B-cells generate random receptors that can in principal see…
kbonham | November 3, 2010[I've been hooked on the immune system since I was a kid and my dad showed me electron micrographs of macrophages eating bacteria in Scientific American. Now that I'm in graduate school studying immunology, and macrophages in particular, my dad asked if I could give a play-by-play of an immune response. Here you go Dad:]
Part 3: Immune memory
Towards the end of the 18th century, Edward Jenner did an experiment. It had long been known that people who had been infected with smallpox, if they managed to survive (no easy feat), would be resistant to further infection. People would even give small…
kbonham | November 3, 2010Viruses are tricky buggers - they force their way into another organism's cell and hijack its machienery to utilize for their own nefarious purposes. This is clearly pretty harmful for the host so there's been pretty strong evolutionary pressure to develop ways to stop them or slow them down (hence the immune system). But in order to do anything, the host first has to recognize that it's infected.
This isn't necessarily as straightforward as it might seem. Viruses (and bacteria and fungus and protists and worms etc) are living things, and use the same molecular building blocks, and many of…
kbonham | November 2, 2010 A while back, ERV had a post about the tenuous link between Vitamin D and all sorts of effects on health (and I shamelessly co-opted her title). Then, PalMD dissected the spurious link between Broccoli and cancer. Now it's my turn:
A new study has revealed that naturally occurring chemicals found in the skin of the nut boost the immune system's response to such infections.
Researchers found almond skins improved the ability of the white blood cells to detect viruses while also increasing the body's ability to prevent viruses from replicating and so spreading inside the body.
Oh Guardian, I…
kbonham | November 2, 2010[I've been hooked on the immune system since I was a kid and my dad showed me electron micrographs of macrophages eating bacteria in Scientific American. Now that I'm in graduate school studying immunology, and macrophages in particular, my dad asked if I could give a play-by-play of an immune response. Here you go Dad:]
Part 2: T-cells, B-cells and adaptive immunity
If you've ever had the flu (and I mean for real influenza, not some sissy man-flu), you know how much it sucks. But don't blame the virus. Many of the most unpleasant symptoms - extreme fatigue, snot-filled sinuses, and high…
kbonham | November 1, 2010[I've been hooked on the immune system since I was a kid and my dad showed me electron micrographs of macrophages eating bacteria in Scientific American. Now that I'm in graduate school studying immunology, and macrophages in particular, my dad asked if I could give a play-by-play of an immune response. Here you go Dad:]
Part 1: Invasion and detection, the innate immune system
Most immunology classes I've taken have begun with a simple, but profound truth: the best immune response is one that prevents pathogens from ever gaining entry (pathogen = disease-causing organism). Hence, we are…