So after having studied HIV for a bit, I found that there is no way HIV can enter the brain through T4 cells, since they cannot pass the Blood Brain Barrier. However, they are able to do so through macrophages. That being said, I am currently studying a protein on microglia called TREM2 and how expression of the receptor results in increased T4 cell proliferation. These Microglia can differentiate into macrophages within the brain, since they are resident macrophages(meaning they NEVER leave the brain). My question is, how in the WORLD can they get a T4 cell response within the brain? The thing is that TREM2 is studied because of it’s effects in alzheimer’s disease, where you have all these protein aggregates in the brain and because of the microglia, which phagocytose and present these as antigens on their surface, T4 CELLS MUST BIND TO THEM AT THIS POINT TO INITIATE AN IMMUNE RESPONSE! But how the hell is this possible if T4 cells can NEVER infiltrate the brain? Thank you.
P.S my professor already knows how it can(IT CAN), I just need help understanding how.
Sensory circumventricular organs (CVO) are specialized areas of the brain that lack a normal blood-brain barrier, and therefor are in constant contact with signaling molecules circulating in the bloodstream.
Area Postrem is a medulary structure lying at the base of the fourth ventricle. The area postrema’s priviged location outside of the blood-brain barrier makes this sensory cirrcumventricular organ a vital player in the control of the authonomic functions by the central nervous system. By virtue of its lack of tight junctions between epithelial cells in this density vascularized structure and the presence of fenestrated capillaries the substance borne in the blood have direct acsses to the neurons to the brain areas.
that response was way too wordy. Im amazed someone actually speaks the way you do. actually, T4 cells can in fact cross teh BBB, they just dont do it often. the BBB mainly keeps out smaller molecules. That pretty much answered my question. Thanks