Interference No. 102,572
reaction If in an assay, an antibody is used to detect the presence of or quantity of the
antigen which elicited the initial response of the antibody-producing cell used in producing
the hybridoma cell line, practical utility may be shown because the antibody and antigen
which elicited it have a unique relationship and the specificity and sensitivity of that
relationship would be known and used as a control. Where an antigen other that which
elicited the antibody is used, binding may occur, however such binding, that is, cross-
reactivity is not indicative of practical utility but may lead to false positives in diagnostic
testing. Thus, any assay to be reliable requires investigation of the sensitivity and
specificity of the antibody-antigen reaction. On this record, we are unable to conclude that
the testing is adequate since neither a correlation between the test conditions and actual
use conditions is established nor is the sensitivity and specificity of the recombinantly
produced antibody with regard to any antigen and the reformed product and same antigen
established.
Cabilly et al. allege that the authenticity and identity of the cell line from which the
known anti-CEA antibodies and recombinant Ig molecules were derived was attested to by
Shively and his reference to Cabilly et al. CX-4. We do not find this argument persuasive.
Shively provided no specific testimony with respect to CX-4 other than to provide a
statement that a mouse hybridoma cell line was generated, CEA.66-E3, which secretes
antibodies directed against human carcinoembryonic antigen and to parenthetically refer
to CX-4 in that statement. Our review of CX-4 shows it to be an article entitled
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