High affinity is a desirable attribute for many therapeutic antibodies. The availability of high affinity monoclonal antibodies is crucial to the development of targeted immunotherapies. In many immunized animals, however, very high affinity antibodies are rare and standard methods for generating antibodies are inefficient at isolating high affinity antibodies.
Typically, monoclonal antibodies are obtained from mouse hybridomas, which most often result from the fusion of B lymphocytes from immunized mice with murine myeloma cells. The isolation of rare high affinity antibodies by hybridoma technology, however, is not efficient because of throughput limitations on hybridoma culture.
Another approach to producing high affinity antibodies involves the use of display technology to produce a lead antibody candidate from a phage, yeast or mammalian library. Though direct DNA isolation from B cells expressing antibodies may be utilized, DNA libraries are expressed in cell expression systems, such as phage, yeast, or bacterial systems, then “panned” or titrated to select for the antibodies having high affinities. Display technologies can provide high-quality protein libraries, although they provide limited diversity. Consequently, in vitro mutagenesis-based affinity maturation is frequently a next step in generating high affinity antibodies derived from such libraries.
Thus, a need exists for an efficient method to obtain, in quantity, antibodies that have the requisite specificity and high binding affinity in an efficient manner, without the need for several rounds of screening (such as “panning”) or site-directed mutagenesis.