So, I am currently learning about glomerulonephritis and am reading about how immune complex formation/ deposition is one of the general mechanisms of injury for GN. I know that immune complexes can form in the circulation and deposit in the glomeruli OR antigen can deposit in the glomeruli and then antibody binds to the deposited antigen and forms complexes (in situ complex formation).
So, I am confused about whether the diseases caused by in situ complex formation are Type II or Type III hypersensitivity. You could say that it is Type III because immune complexes have to form to cause disease, BUT why wouldn't it be a Type II reaction? Antibodies are binding to an antigen present on host tissue and not forming in the circulation? Isn't that basically defined as a Type II reaction? I was thinking that maybe the distinction was in whether or not the antigen in the tissues was intrinsic or extrinsic but it seems that both Type II and Type III reactions can be triggered by intrinsic or extrinsic antigens.
Maybe I am just not understanding the difference between Type II versus Type III hypersensitivity?
Anyway, I couldn't figure it out even after consulting several sources so I thought I'd see if someone here maybe had a better idea or understanding of the distinction...
So, I am confused about whether the diseases caused by in situ complex formation are Type II or Type III hypersensitivity. You could say that it is Type III because immune complexes have to form to cause disease, BUT why wouldn't it be a Type II reaction? Antibodies are binding to an antigen present on host tissue and not forming in the circulation? Isn't that basically defined as a Type II reaction? I was thinking that maybe the distinction was in whether or not the antigen in the tissues was intrinsic or extrinsic but it seems that both Type II and Type III reactions can be triggered by intrinsic or extrinsic antigens.
Maybe I am just not understanding the difference between Type II versus Type III hypersensitivity?
Anyway, I couldn't figure it out even after consulting several sources so I thought I'd see if someone here maybe had a better idea or understanding of the distinction...