On pages 12-13, Dr. Moalem
describes how the ability to access iron within our macrophages is what makes
some infections deadly. Macrophages are the police of the immune system. They
search our systems looking for trouble and when they find it, they try to
subdue or kill it. This relates to big idea 4: biological systems interact, and
these systems and their interactions possess complex properties. Explain why if
your macrophages lack iron, why those have an additional advantage. Why is it
that the excess iron that the body takes on isn’t distributed everywhere
throughout the body. How does this hinder other biological systems within the
body?
Many infectious agents can use the iron within the microphage to multiply. A normal macrophage can gather up certain infectious agents to protect the body, but the macrophage is essentially giving the agents a Trojan horse access to the iron they need to feed and multiply. Explain how this relates to what happened with the bubonic plague.
(Josh Baker jbaker3@students.d125.org)
As we have just learned from our new unit, macrophages, or ‘big eaters,’ are a part of nonspecific immunity. As part of their function, macrophages ‘eat’ the foreign antigen then break it down using enzymes to destroy it. As in relation to lacking iron, this has a lot to do with what Dr. Moalem said about infections being able to feed off of the iron carried by macrophages to divide and multiply (13). This means that having iron-deficient macrophages is advantageous because the antigen is unable to feed off of the macrophages to survive. Because macrophages approach the harmful antigen, it would normally be very easy for the infection to find take that iron and use it. If those same macrophages surround the same antigen but lack iron (like in hemochromatosis patients), then the infection cannot feed and multiply thereby killing it by starvation.
ReplyDeleteThe reason for the uneven distribution of iron throughout the body is unknown. The only truly known factor is that the iron is unevenly distributed and the macrophages receive very little (the following sites were looked at to determine cause of uneven distribution: http://www.med.uottawa.ca, http://www.ncbi.nlm.nih.gov, radiopaedia.org); however, it also known that because of this uneven iron distribution and subsequent iron overload, organs like the heart and liver and pancreas are damaged (cddc.gov). These organs are highly affected and damaged by iron overload because they are the storage places for the iron. This is bad for these organs because excess iron invites antigens and harmful bacteria to attack and feed and therefore grow, damaging the organ.
As for the Trojan horse affect, the way macrophages contributed to the bubonic plague was not necessarily ‘tricking’ the infectious agents into believing they had iron to feed off of but rather was by depriving the antigens of the iron they need to multiply. Macrophages do occasionally take the ‘driver’s license’ from the antigen and attach it to its membrane, but this is used more for protection, to add onto the membrane of the macrophage, and to signal for specific immunity response. This reaction is a demonstration of Big Idea 4 because the non-specific immunity signals specific immunity to begin. The importance, however, of the macrophages in the bubonic plague has less to do with specific immunity and more to do with hemochromatosis patients lacking the iron the infection would normally use to spread.
(Morgan Eisenstot – meisens4@students.d125.org)