> Purified antibodies are required for a number of techniques.Figure 24 lists several techniques that require purified antibodies at least in certain steps of the procedure.Many of the antibodies in Figure 24 are labeled with a tag and these labeled antibodies are then used to determine the presence of antigen or another antibody.When labeled anti-immunoglobulins antibodies are needed it is seldom worthwhile to prepare and label the reagents yourself.These reagents are prepared commercially and tested by a number of companies.When the antibody is used to detect the antigen direclty;the antibody must be purified and labeled.Directly labeling also allows two different antibodies to be compared in the same assay by marking them with different tags.In many procedures purified antibodies may lower the background activity of the assay.Purification may be the easiest way to concentrate the antibody. There are a wide variety of methods used to purify antibodies.The correct choice of purification will depend on a number of factors:(1)the manner in which the antibody will be used;(2)the species in which antibody was produced;(3)the class and subclass that will be used;(4)the type of antibody that is needed monoclonal or polyclonal antibody;and (5)the source (ascities or tissue culture fluids)that will serve as the starting material for the purification.Table 25 summarizes the possible sources of antibodies for purification.Also included in this table are the possible sources of antibody contamination and the expected level of purity.> Purified antibodies are required for a number of techniques. Figure 24 lists several techniques that require purified antibodies at least in certain steps of the procedure. Many of the antibodies in Figure 24 are labeled with a tag and these labeled antibodies are then used to determine the presence of antigen or another antibody. When labeled anti-immunoglobulins antibodies are needed it is seldom worthwhile to prepare and label the reagents yourself. These reagents are prepared commercially and tested by a number of companies. When the antibody is used to detect the antigen direclty; the antibody must be purified and labeled. Directly labeling also allows two different antibodies to be compared in the same assay by marking them with different tags. In many procedures purified antibodies may lower the background activity of the assay. Purification may be the easiest way to concentrate the antibody. There are a wide variety of methods used to purify antibodies. The correct choice of purification will depend on a number of factors: (1) the manner in which the antibody will be used; (2) the species in which antibody was produced; (3) the class and subclass that will be used; (4) the type of antibody that is needed monoclonal or polyclonal antibody; and (5) the source (ascities or tissue culture fluids) that will serve as the starting material for the purification. Table 25 summarizes the possible sources of antibodies for purification. Also included in this table are the possible sources of antibody contamination and the expected level of purity