Threshold ligand-receptor assay

Method for determining the amount of at least one target ligand, capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand analogue conjugate and said ligand receptor to form a homogeneous reaction mixture, the relative amounts of said ligand analogue conjugate and said ligand receptor being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand analogue conjugate is bound to said ligand receptor such that no unbound ligand analogue conjugate is detected as a result of the assay method;
• b. removing ligand receptor from said reaction mixture;
• c. detecting unbound ligand analogue conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand in said fluid sample.

Method for determining the amount of at least one target ligand, at or above at least one predetermined threshold ligand concentration, said target ligand capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand analogue conjugate and said ligand receptor to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand analogue conjugate and said ligand receptor being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand analogue conjugate is bound to said ligand receptor such that no unbound ligand analogue conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of ligand analogue conjugate and ligand receptor being selected such that at least one of said predetermined threshold ligand concentration is established below which no unbound ligand analogue conjugate is detected as a result of the assay method;
• b. detecting unbound ligand analogue conjugate in said reaction mixture;
• c. relating the detectable signal to the amount of said target ligand at or above said predetermined threshold ligand concentration in said fluid sample.

Method for determining the amount of at least one target ligand at or above at least one predetermined threshold ligand concentration, said target ligand capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand analogue conjugate and said ligand receptor to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand analogue conjugate and said ligand receptor being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand analogue conjugate is bound to said ligand receptor such that no unbound ligand analogue conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of ligand analogue conjugate and ligand receptor being selected such that at least one of said predetermined threshold ligand concentration is established below which no unbound ligand analogue conjugate is detected as a result of the assay method;
• b. removing ligand receptor from said reaction mixture;
• c. detecting unbound ligand analogue conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand at or above said predetermined threshold ligand concentration in said fluid sample.

Method for determining the amount of at least one target ligand receptor, capable of competing with a ligand receptor conjugate for binding sites available on a ligand analogue construct, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand receptor, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture, the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand receptor, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method.
• b. removing ligand analogue construct from said
• c. detecting unbound ligand receptor conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand receptor in said fluid sample.

Method for determining the amount of at least one target ligand receptor at or above at least one predetermined threshold ligand receptor concentration, said target ligand receptor capable of competing with a ligand receptor conjugate for binding sites available on said ligand analogue construct, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand receptor, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand receptor, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of ligand receptor conjugate and ligand analogue construct being selected such that at least one of said predetermined threshold ligand receptor concentration(s) is established below which no unbound ligand receptor conjugate is detected as a result of the assay method;
• b. detecting unbound ligand receptor conjugate in said reaction mixture;
• c. relating the detectable signal to the amount of said target ligand receptor at or above said predetermined threshold ligand receptor concentration(s) in said fluid sample.

Method for determining the amount of at least one target ligand receptor at or above at least one predetermined threshold ligand receptor concentration, said target ligand receptor capable of competing with a ligand receptor conjugate for binding sites available on a ligand analogue construct, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand receptor, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand receptor, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of said ligand receptor conjugate and ligand analogue construct being selected such that at least one of said predetermined threshold ligand receptor concentration(s) is established below which no unbound ligand receptor conjugate is detected as a result of the assay method;
• b. removing ligand analogue construct from said reaction mixture;
• c. detecting unbound ligand receptor conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand receptor at or above said predetermined threshold ligand receptor concentration(s) in said fluid sample.

Method for determining the amount of at least one target ligand, capable of competing with a ligand analogue construct for binding sites available on a ligand receptor conjugate, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture, the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method;
• b. removing ligand analogue construct from said reaction mixture;
• c. detecting unbound ligand receptor conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand in said fluid sample.

Method for determining the amount of at least one target ligand at or above at least one predetermined threshold ligand concentration, said target ligand capable of competing with a ligand analogue construct for binding sites available on a ligand receptor conjugate, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of ligand receptor conjugate and ligand analogue construct being selected such that at least one of said predetermined threshold ligand concentration(s) is established below which no unbound ligand receptor conjugate is detected as a result of the assay method;
• b. detecting unbound ligand receptor conjugate in said reaction mixture;
• c. relating the detectable signal to the amount of said target ligand at or above said predetermined threshold ligand concentration(s) in said fluid sample.

Method for determining the amount of at least one target ligand at or above at least one predetermined threshold ligand concentration, said target ligand capable of competing with a ligand analogue construct for binding sites available on a ligand receptor conjugate, said ligand receptor conjugate comprising at least one ligand receptor coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:

• a. contacting said fluid sample with said ligand receptor conjugate and said ligand analogue construct to form a homogeneous reaction mixture;
• (i) the relative amounts of said ligand receptor conjugate and said ligand analogue construct being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand receptor conjugate is bound to said ligand analogue construct such that no unbound ligand receptor conjugate is detected as a result of the assay method;
• and
• (ii) the relative and absolute amounts of ligand receptor conjugate and ligand analogue construct being selected such that at least one of said predetermined threshold ligand concentration(s) is established below which no unbound ligand receptor conjugate is detected as a result of the assay method;
• b. removing ligand analogue construct from said reaction mixture;
• c. detecting unbound ligand receptor conjugate in said reaction mixture;
• d. relating the detectable signal to the amount of said target ligand at or above said predetermined threshold ligand concentration(s) in said fluid sample.

Method for determining the amount of at least one target liquid, capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid sample, comprising the steps of:

• a. contacting said fluid sample with said ligand analogue conjugate and said ligand receptor to form a homogeneous reaction mixture,
• (i) the relative amounts of said ligand analogue conjugate and said ligand receptor being selected such that in the absence of said target ligand, and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand analogue conjugate is bound to said ligand receptor such that no unbound ligand analogue conjugate is detected as a result of the assay method;
• and
• (ii) the relative amounts of ligand analogue conjugate and ligand receptor being selected such that at least one predetermined threshold ligand concentration is established below which no unbound ligand analogue conjugate is detected as a result of the assay method:
• b. detecting unbound ligand analogue conjugate said reaction mixture;
• c. relating the detectable signal to the amount of target ligand in said fluid sample using the relationship that when the affinity of receptor for ligand analogue conjugate is at least 50 times greater than the inverse of the receptor concentration, then the ratio of free to bound ligand analogue conjugate is a linear function of ligand concentration over substantially the entire assay range.