Antibodies primary, secondary responses

The secondary response is also known as booster response. It differs from primary response and has a shorter latent period, production of antibodies is more rapid, antibodies are more abundant, antibody response is maintained at a higher level for a longer period and antibodies elicited tend to have a greater capacity to bind to the antigen. 

Antibody levels. The antibody levels are 10 times higher in the secondary response compared to the primary response. 

Antibody class. The major proportion of the primary response is made up of IgM, whereas the secondary response consists almost entirely of IgG. 

Antibody affinity. The affinity of the antibodies is much greater in the secondary response as opposed to the primary response, which is termed affinity maturation. ... 

Kinetics of the immune response by antibodies Following the first exposure of an individual to an unknown antigen, the first occurrence of specific IgG can be detected approximately three weeks later (primary response). If these particular antigens appear in the body for a second time, however, IgG will be produced much more rapidly and in larger amounts to eliminate the antigen (secondary response). 

Hoffman et al.52, presented evidence that a single oral dose of tilorone enhanced the primary immune response to sheep red blood cells (SRBC) in mice as measured by the Jerne Plaque technique. They also reported an increase in hemolysin titer after tilorone administration. To further evaluate the action of tilorone on humoral antibody responses, Megel ef a/.3 have studied its effect on 19S and 7S production in the primary and secondary immune responses in mice. It was found that tilorone elevated 19S antibody titer on days 3 and 4 after immunization. After 9 days of continuous drug administration, the 19 S response for both groups was diminished compared to days 3 and 4 however tilorone was found to cause a significant increase in the 7S antibody production compared to controls. Tilorone also stimulated the 19S response to E. coli endotoxin, a thymus-independent antigen, on days 3 and 4 after immunization. 

IgM is the dominant antibody produced in primary immune responses, while IgG dominates in secondary immune responses. IgM is physically much larger than the other immunoglobulins. 

The secondary response results from the readministration of antigen at a later time and is characterized by a rapid increase in antibody levels consisting mainly of IgG, but with some transient IgM. The most striking effect observed is the great increase in total serum antibody levels over that obtained in the primary response (Fig. 3). After 2-3 weeks there is a... 

Delayed reactions are difficult to prevent. Incompatibility may not be demonstrable before transfusion, and at the time of the reaction the relevant antibodies may not be detectable. Post-transfusion blood samples must therefore be subjected to repeated serological testing. Delayed reactions usually occur as a result of a secondary anamnestic response within 3-21 days after the transfusion of apparently compatible blood, at a time when the antibody concentration has risen sufficiently to bring about hemolysis of the donor s erythrocytes. A primary immune response can also evoke this kind of reaction (61). 

A primary response of the humoral system involves a significant latent period before elevated serum antibody levels are seen the major serum antibody generated is IgM. Memory cell populations provide the basis of the secondary response, which displays a significant reduction in the latency period to achieve elevated serum antibody. The antibody serum levels are greater than in the primary response and involve mainly IgG. 

Secreted antibody, in particular IgG, IgA and IgM, can bind antigen and sterically hinder the interaction of toxins, viruses, bacteria, etc. with host cell surfaces. In the circulatory and interstitial fluids IgG (which exists as a monomer with an antigen valency of 2) is the main antibody that fulfils this role in the secondary response, while IgM is the main antibody produced in the primary response. IgA has specific roles in mucosal immunity. 

Humoral immune responses can be divided into two types primary and secondary responses, which reflect the cellular dynamics of the immune system and the immune state of the host. A primary response is caused by the first exposure to a given immunogen and results in the appearance of predominantly IgM antibodies after a relatively long lag period, followed by a peak and a decline of antibody formation. After a lapse of time, another exposure to the immunogen produces a quite different, secondary response which is characterized by a shorter lag period, a stronger response with predominantly IgG antibodies and, after a peak has been reached, a slower decrease. 

Fig. 6.8 Primary antibody response in mice (open circles) after a single vaccination with a plasmid encoding y -galactosidase and secondary response (filled circles) after challenge with y -galactosidase...

Vaccination prepares bodily defenses and stimulates the production of antibodies by the lymphocytes. When the animal encounters an antigen for the first time, it responds with a small primary response. If it encounters the antigen again soon after, the so-called secondary response is much larger, much quicker, and more prolonged. 

Other in vitro assays have been developed, which use animal cells, for example, an assay developed by Fischer et al.(2011), which uses rodent blood cells and splenocytes exposed to sheep red blood cells, and the Mishell-Dutton assay, which is an in vitro immunization culture system measuring an primary antibody responses of mouse splenocytes (Michell and Dutton, 1967). Although the HuLA assay of Collinge et al. (2010) only measures the secondary response, it has advantages over these in vitro methods in that it uses human cells and a human disease-relevant antigen. 

In Figure 5.16 is reported the antibody response to Limulus polyphemus haemocyanin measured by passive haemagglutination. The superiority of the High line in both primary and secondary responses is evident. 

Table 5.7 Primary and secondary responses to DNP—BGG serum concentration and characteristics of antibody produced...

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