1. Claim interpretation
For the purpose of the description requirement issue, Engvall’s claim 17 is representative.
We have reproduced claim 17 below, adding indentation for clarity:
17. 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 of8
said labeled antibody and said antibody bound to a
solid carrier. [Emphasis added.]
As we did with the count, we construe the phrase “at least about 10 liters/mole” as indicating a8
lower limit for the range of the affinity necessary to use the claimed invention. We interpret “10 ” 8
to mean 1 x 10 . The phrase “at least” indicates the stated affinity constant is a minimum value. The8
word “about” adds some imprecision and extends the minimum affinity constant to a value somewhat
8 8
below 1 x 10 . In other words, we interpret “at least about 10 liters/mole” to indicate a range
8
beginning somewhat below 1 x 10 liters/mole and extending to 4.
a. The materiality of the affinity limitation
In opposing David’s motion, Engvall argued that the affinity limitation of claims 8 to 27 is not
material. Paper 39, pp. 3-8. Implicitly, Engvall asserts that the purported lack of materiality excuses
Engvall from the written description requirements of 35 U.S.C. § 112, ¶ 1. The statute and the case
law interpreting the statute are clearly to the contrary. The first paragraph of § 112 expressly requires
that the “specification shall contain a written description of the invention....” It is well settled that
the “invention is, for the purpose of the 'written description' inquiry, whatever is now claimed.” Vas-
13
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