EXERCISES, LESSON 5
INSTRUCTIONS: Answer the following items by completing the statement or by writing
the answer in the space provided.
After you have completed all of these items, turn to "Solutions to Exercises" at the
end of the lesson and check your answers with the solutions.
You will be better able to interpret and apply the new knowledge about
immunology as you develop an understanding of the m__s now in use. In this
lesson, the techniques and applications of the various i______cal tests for the
detection of a____s and a____s are discussed.
In Marrack's model, under appropriate experimental conditions, antigen-antibody
complexes p___tate. Antibody molecules are bivalent, that is, they contain two
a____n-binding sites. At a proper antigen and antibody concentration, a cross-
linked m___s enlarges and p_____s.
At the onset of the antigen-antibody reaction, an i_____ble formation of antigen
and antibody complexes occurs. This is followed by an expanding visible
precipitate, called a l____ce f____tion, as the antigen and antibody reach a zone
of equivalent concentration. If there is an excess of either antigen or antibody
present, the proper l___ce formation needed for precipitate formation cannot
occur. The formation of the antigen-antibody complex is r____ble and may
d___ve if more antigen or antibody is added.
Immunodiffusion techniques detect antigen-antibody precipitation reactions in a
semis____d medium. The formation of antigen and antibody complexes can be
influenced by a number of factors: relative c____tion of antigens and antibodies,
i__c s____th of the buffer, pH, and t_____e. Two techniques most often used in a
clinical laboratory are s____le and d___le diffusion.
In the r___l immunodiffusion (RID) method, a known concentration of antibody is
incorporated into an agarose m__m. The reactant (antigen) is applied to a well cut
in the a___e and radially diffuses from the site of application. At the point of
e______ce, the antigen and antibody react to form a visible p___tin ring. The size
of the precipitin ring is proportional to the c_____tion of the antigen. In the clinical
laboratory, radial immunodiffusion is primarily used to quantitate serum i____lins
and c______t components such as C3 or C4.