Page 153 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

I. General characteristics of the antibody response

A. Self/non-self discrimination - It normally distinguishes between self and non-

self and only reacts against non-self.
B. Memory The immune system "remembers" if it has seen an antigen before and

it reacts to secondary exposure to an antigen in a manner different than after a

primary exposure.
C. Specificity - There is a high degree of specificity. A response to a particular

antigen is specific for that antigen or a few closely related antigens.

Primary and Secondary Responses to Antigen

- In the primary response the major class of Ab produced is IgM whereas in the
secondary response it is IgG

-The antibodies that persist in secondary response are the IgG antibodies.

Notice four key differences between the primary and secondary antibody

response. On the secondary response:

• The lag time before the appearance of antibodies is shorter.
• The peak titer is much higher.

• IgG antibodies predominate; and antibodies bind more strongly to the antigen.

• The high levels of IgG antibodies are maintained for longer.

General Microbiology & Immunology (PM 401) theoretical handbook Page 142