be free of said antigenic substance, to determine the presence of
antigenic substance in said fluid sample, or relating the amount of
labeled antibody measured with the amount of labeled antibody
measured for samples containing known amounts of antigenic
substance prepared in accordance with steps (a)-(d) to determine the
concentration of antigenic substance in said fluid sample.
19. In an immunometric assay to determine the presence or
concentration of an antigenic substance in a sample of a fluid
comprising forming a ternary complex of a first labeled antibody, said
antigenic substance, and a second antibody said second antibody being
bound to a solid carrier insoluble in said fluid wherein the presence of
the antigenic substance in the samples is determined by measuring
either the amount of labeled antibody bound to the solid carrier or the
amount of unreacted labeled antibody, the improvement comprising
employing monoclonal antibodies having an affinity for the antigenic
substance of at least about 10 liters/mole for each of said labeled8
antibody and said antibody bound to a solid carrier. [Emphasis
added.]
2. David’s semi-automatic screening assay
Engvall asserts that the David inventors withheld the best mode of practicing their invention.
In particular, Engvall alleges that in order to practice the claimed method, it is necessary to screen
for monoclonal antibodies which have an affinity constant of at least about 10 liters per mole for the8
antigenic substance of interest . Engvall points out that David had a semi-automatic assay for
performing this function when the David application was filed, that David acknowledged that the
semi-automatic screening assay was the best approach to the screening procedure, and that David’s
specification did not disclose this semi-automatic technique. Engvall further alleges that David’s
disclosed a different less advantageous technique and that David desired to keep the semi-automatic
assay technique a trade secret shows an intent to conceal the best mode. Engvall Brief, pp. 122-125.
3. Analysis
The first paragraph of 35 U.S.C. § 112 provides:
The specification shall contain a written description of the invention,
and of the manner and process of making and using it, in such full,
clear, concise, and exact terms as to enable any person skilled in the
art to which it pertains, or with which it is most nearly connected, to
make and use the same, and shall set forth the best mode
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