Handout 16, Figure 1

During a primary immune response, mostly IgM class antibodies are produced during the early stage. This happens because there are a low amount of B cells and T cells due to the present of a non-replicating protein antigen being introduced for the very first time into the body. After about 5-7 days, maturation time for cells, antibody to the antigen will peak and then decline. During this decline stage, class switch of IgM to IgG may occur. The amount of IgG present depends mainly on the type and amount of antigen being inoculated.