There have been very few developments that markedly affect the need to
greatly revise the text from the last version of this book. This is
testament to the fact that hetero- neous enzyme-linked immunosorbent
assays (ELISA) provide ideal systems for dealing with a wide range of
studies in many biological areas. The main reason for this success is
test flexibility, whereby reactants can be used in different
combinations, either attached passively to a solid phase support or in
the liquid phase. The exploitation of the ELISA has been increased
through continued development of specifically produced reagents, for
example, monoclonal and polyclonal antibodies and peptide antigens
coupled with the improvement and expansion of commercial products such
as enzyme-linked conjugates, substrates and chromogens, plastics
technology and design of microwell plates, inst- mentation advances and
robotics. However, the principles of the ELISA remain the same. There
has been some rearrangement of chapters plus addition of three new ones
dealing with charting methods for assessing the indirect ELISA,
ruggedness and robustness of tests-aspects of kit use and validation,
and internal quality control and external quality management of data,
respectively. These reflect the need to control what you are doing with
ELISA and to exploit the method to its full extent. I do not apologize
for dealing with the same areas in different ways a number of times, as
it is imperative that principles are understood to allow planning,
operation, and control of ELISA.
