‘Antibodies for every possible antigen?‘ Sharks can apparently do this. Humans? Maybe not.
‘Will every human have an antibody that will be effective for a given pathogen?‘ No and neither is this necessary because
- As the body’s safeguard against deadly pathogens, nowhere is the adage to not pull all one’s eggs in one basket truer than for the immune system.
- Thus, the immune system has in-built necessary redundancy.
- As such, antibody is just one among many types of immune responses the body’s capable of, CD4, CD8 T cells, NK (natural killer) cells, these are some of the other types of immune cells with specific diversified receptors with the former, i.e., CD4 and CD8, also undergoing extensive VDJ recombination, similar in process to antibodies.
- Antibodies are not always the most effective immune response. For e.g., active TB patients make a lot of anti-TB antibodies which are obviously ineffective in controlling the disease.
‘Or since VDJ recombination kind of produces random antibody structures and might not happen to produce the needed antibody‘. VDJ recombination expands antibody specificity, i.e., capacity to bind specifically to an antigen, iterated for millions of different antigens. However, the outcome of VDJ recombination isn’t random. The process of B cell tolerance deletes those making antibodies that bind to self-antigens. As well, most organisms express thousands of antigens. Chance combined with VDJ recombination more or less ensures that there’d be antibodies against at least a few if not against most of the antigens expressed by a particular organism.
‘Or given enough time everyone will everyone come up with an effective antibody?‘ Specificity, i.e., the antigen an antibody binds to, is only one part of what makes an antibody effective. Often antibody class, i.e., isotype, is the other critical issue. Too much of the wrong antibody class can be just as bad or even worse than not making any. For someone who suffers from allergies, allergens aren’t the problem so much as pathogenic/damaging antibodies, i.e., an antibody class such as IgE, which perpetuates the vicious cycle of allergy symptoms. OTOH, non-allergic people also make antibodies specific for the same allergens. Only far fewer of them are IgE. Thus, effectiveness of an antibody response depends on both how it’s regulated by other elements of the immune system as what the antibody’s specific for. In the case of the antibody class, this effectively means the kind of CD4 T cell help that the B cell making the antibody receives.