Primary and Secondary Antibody Responses

After administration of an antigen for the first time, there is an initial lag phase where antibodies are not produced. This is followed by a period in which the antibody titer rises logarithmically to a maximum and subsequently declines. The decline is due to either the breakdown or the clearance of the antibodies. 

The primary and secondary responses differ in the following four ways  

Time course. The secondary response has a shorter lag phase and an extended plateau and decline. 

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. 

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Significant decrease in NK activity significant decreases in ex vivo prohferative responses to ConA and LPS significant decreases in primary and secondary antibody responses to T cell-dependent antigens... 

Significant decreases in ex vivo proliferative responses to ConA and LPS significant decreases in primary and secondary antibody response to T cell-dependent antigens Significant decrease in absolute number of peripheral blood T cells (CD3, CD4, and CDS) and B cells and in percentage of CD3 T lymphocytes (associated with decrease in CD4 valnes) in spleen and (CD4 and CDS valnes) in axillary lymph node Decreases in IgM and IgG antibody response to KLH Dose-related decrease in splenic and mesenteric lymph node T cells and CD4 T cells... 

Methotrexate is a folic acid antagonists that indirectly suppresses the synthesis of purine and is particularly effective in rapidly proliferating cell populations such as cancer. It depresses the primary and secondary antibody response, the homograft reaction, the graft-versus-host response, and the development of hypersensitivity. Methotrexate is used in the treatment of certain cancers. It is very toxic in long-term use, especially to the liver. The toxic effect of methotrexate is reversed by use of... 

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. 

Figure 6-2. Primary and secondary immune responses. After the first exposure to antigen, antibody production in the animal is stimulated. In the primary response, antibodies of low affinity and specificity are produced in relatively low...

Courtenay-Luck NS, Epenetos AA, Moore R, Larche M, Pectasides D, Dhokia B, Ritter MA. Development of primary and secondary immune responses to mouse monoclonal antibodies used in the diagnosis and therapy of malignant neoplasms. Cancer Res 1986 46(12 Pt l) 6489-93. 

In a study utilizing over 4000 mice (Spallholz et al., 1974) where the route of administration (ip, sc or intradermal) of Se and Vitamin E (0-100 yg Se and /or 0-5 mg Vitamin E) upon the primary and secondary immune responses to SRBC antigens or tetanus toxoid (TT) were studied, synergism between Se and Vitamin E in increasing antibody titers was observed. No increases in anti-TT titers were observed in the primary immune response, but were increased in the secondary immune response. Anti-SRBC antibodies were enhanced in both primary and secondary immune responses. The primary Immune response to both antigens was measured over a 21-day period while the secondary response was also measured over 21-day period following the second immunization-sensitization. 

Thus, human exposure to PCBs in Japan (Yusho accident) and China has been associated with increased respiratory infections and decreased levels of immunoglobulins in serum. In animals exposed to these compounds, there is atrophy of both primary and secondary lymphoid organs, lower circulating immunoglobulins, and decreased antibody responses after exposure to antigens. Similarly, the exposure of both humans and farm animals to polybrominated biphenyls, which occurred in Michigan in 1973, resulted in depressed immune responses. 

Fig. 14.1 Primary and secondary lymphoid organs. The primary lymphoid organs are the tissues where the lymphocytes develop from haematopoietic stem cells. The encounter with antigen, the immune response, occurs in the peripheral, secondary lymphoid organs. T cells are responsible for the cell-mediated immune response and B cells for the antigen-stimulated synthesis and secretion of circulating antibodies.

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. 

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. 

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