Immunological Memory

IMMUNOLOGICAL MEMORY

It has been well established and proved beyond any reasonable doubt that the intensity of the humoral response gets adequately reflected by the ‘antibody titer’, that accounts for the total quantum 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 and foremost IgM antibodies are produced and subsequently IgG antibodies, as illustrated in Fig. 9.3.

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 (see Section 1.3).

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 response as depicted in Fig. 9.3.