response
of
antibody** present in the serum. Soonafter the very first initial contact with an antigen, the serum of
the exposed person emphatically comprises of absolutely no detectable antibodies upto even several
days at a stretch. However, one may distinctly notice a gradual rise in the
‘antibody titer’ i.e., first andforemost IgM*** antibodies are produced and subsequently IgG****
Ultimately, a slow decline in antibody titer takes place. Importantly, the ensuing pattern of decline
duly designates the characteristic feature of a
primary response to an antigen. However, the immune
responses
of the host gets adequately intensified immediately after a second exposure to an antigen.Nevertheless, this secondary response is usually termed as memory or anamnestic response
It has been observed that there exists certain
activated B lymphocytes that fail to turn into the so
called
antibody-producing plasma cells, but do persist and sustain as the long-lived memory cells.
After a long span even stretching over to several decades, when such
‘cells’ are duly stimulated by the
‘same antigen’
, they invariably tend to differentiate rapidly into the much desired antibody-producing
plasma cells.
Actually, this ultimately affords the fundamental basis of the secondary immune responseas depicted