Through this process, B cells function as APC for T cell activation. Antibodies are proteins called Immunoglobulins Igs found in the plasma. We have 5 classes of antibodies and subclasses. IgM IgA IgD IgA 4. Antibodies are hard to purify.
Same class have same characteristics.
Antibodies are purified in very low concentration. If we want to under stand antibodies we must study them in pure form. A homogenous mixture of antibodies are needed.