A study found that vaccine recipients with high levels of IgA antibodies to gp12
ID: 219240 • Letter: A
Question
A study found that vaccine recipients with high levels of IgA antibodies to gp120 surface antigen (referred to as Env) had a higher risk of HIV infection than vaccine recipients with lower levels of IgA. They speculated that IgA could be outcompeting other antibodies with respect to antigen binding. Why might this be detrimental to generating a protective immune response? A study found that vaccine recipients with high levels of IgA antibodies to gp120 surface antigen (referred to as Env) had a higher risk of HIV infection than vaccine recipients with lower levels of IgA. They speculated that IgA could be outcompeting other antibodies with respect to antigen binding. Why might this be detrimental to generating a protective immune response?Explanation / Answer
Immunoglobulin A (IgA) is an antibody thatis crucial for the immune function of mucous membranes and is found in tears, saliva, sweat, colostrum and secretions from the genitourinary tract, gastrointestinal tract, prostate and respiratory epithelium.?
THerefore IgA is the anitbody that the body produces to clear out infections on the mucous membranes.
HIV vaccine is administered orally using a gp120 surface antigen that induces HIV-specific IFN-?-producing CD4+ and CD8+ effector memory T cells.
Let us assume thata person has a higher level of IgA antibody against gp120 surface antigen. When the vaccine is administered, the IgA beibg in high amounts, binds to these antigens and clears them quicly, even before that effector memory T cells are formed.
However if the same vaccine is administered to a person with low levels if IgA, the body takes time to clear these antigens. During this time the body develop memory T-cells. These T-cells "remember the antigen" and when face the same antigen during a subsequent infection are more effective in clearing the virus.
Hence a person with low IgA, has time to develop memory T-cells that produces a long lasting protection against the virus and therefore it is speculated that high IgA might be detrimental to generating a protective immune response
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