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is easy to accept that no two lymphocytes, even under identical
circumstances, will ever produce the same antibody or the same
specifi c receptor. The evolutionary signifi cance of this is that the
assembly of germ line information in the paratopes is a somatic
deed and this introduces stochasticity. A signifi cant feature of
the system is that it lets specifi city be managed by single cells
which, as a rule, carry just one type of receptor and therefore
one specifi city. This is a great solution, but is also a limitation
in the expression of full immune potential. In man, lymphocytes
are probably in the order of a billion, and account for half of the
entire weight of the lymphoid tissue, but many of them are part
of clones (e.g., in the case ...