Does our immune system not work with STDs? I am learning about our immune system and how our antibodies work. I don’t understand what happens in which we are able to get re-infected with certain infectious disease if we should have immunity. Im guessing our immune system just doesn’t work properly against these infections?
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The short answer is : it has to do with your memory B cells and memory T cells, probably
The long answer : whenever our immune system comes in contact with a pathogen (disease causing micro-organism), neutrophils and lymphocytes ( among other WBCs) come into action and depending on the type of pathogen (bacteria vs virus) different cells come into play.
Neutrophils are fast acting and ‘eat’ (phagocytose) the foreign organism quickly and without any specificity IF THE IMMUNE SYSTEM IS ABLE TO DETECT IT EARLY( will come back to this part later) —— so it is called innate immunity.
Lymphocytes (both B and T) forms what we call active/adaptive immunity. If exposed to a very specific pathogen (or a part of it/its product called an antigen) they form antibodies which attack the said pathogen. Now the thing about these lymphocytes, when exposed to an antigen in a sufficient amount (by natural infection or vaccination) a small portion of them instead of forming antibody cells, form what we call memory cells which remembers that specific antigen/pathogen and if encounters it again produces a MASSIVE response that the person won’t even feel a little sick.
It just so happens that against measles, mumps and certain viruses these lymphocytes have a tendency to form more memory cells as compared to infections with bacteria like syphilis, gonorrhea and strep. Now why these memory cells choose to form memory cells for some pathogens and not others comes down to genetics and the individual’s physiology.
The thing is and this is where speculation comes in ,bacterial infections (syphilis, strep, etc) don’t really need these energy expensive memory cells because they are easy to detect and kill because they are living cells with easily detectable biological processes and life cycle and the way they cause the disease, so it’s a lot easier to just attack them randomly with neutrophils and hence the immunity is short lasting and re-infection with the same strain might occur and different bacteria have some similarities in their structure so fast, non-specific approach works.
Viruses on the other hand are non-living until they infect a host cell when they become alive and part of the cell/body they infected (us), since viruses assimilate their DNA into our cells it might have been harder for the immune system to detect that something is off or wrong because well the cell the virus infected TECHNICALLY belongs to us and by the time the immune system kicks in, virus has multiplied a lot and have killed the cell and spread to other parts through blood.
So evolutionarily, it might have made sense to save these memory cells for these kind of viruses/pathogens that are not detectable easily, so if and when they get detected, the response is strong. Also, it might also be possible we keep getting infected with these from time to time and each time the memory cell kick in and kill them before we even get sick and the immunity kinda resets.
As I said it’s mostly speculation after the genetics of the memory cells part. But these are my thoughts
Hope this helps, feel free to ask any questions:)
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