Methods for detecting sepsis
Compositions and methods for detecting sepsis by contacting a subject-derived sample with a ligand that binds to GRK and determining the concentration of GRK in the sample. An increase in the concentration of GRK compared to that of a normal, healthy control sample indicates that the subject from which the sample is obtained is suffering from or at risk of developing sepsis.
1. A method for detecting sepsis or a risk of developing sepsis in a subject, comprising
contacting a subject-derived sample with an isolated antibody or with a GRK binding fragment of said antibody that binds to both a complex of granzyme K protein (GRK)/GRK inhibitors and uncomplexed GRK, wherein the binding specificity of said antibody or said GRK binding fragment thereof consists of one or more GRK epitope(s) contained in residues 182-197 of SEQ ID NO:1 or residues 189-205 of SEQ ID NO:1,
determining binding of said antibody or said binding fragment to GRK in said sample to determine a level of total or uncomplexed GRK in said sample,
and detecting sepsis or a risk of developing sepsis in the subject by detecting an increase in the level of total or uncomplexed GRK in said subject-derived sample compared to that of a normal control level of GRK.
2. The method of claim 1 , wherein said subject is a human.
3. The method of claim 1 , wherein said subject is a human infant.
4. The method of claim 1 , wherein said sample is blood.
5. The method of claim 1 , wherein said sample is plasma.
6. The method of claim 1 , wherein said sample is serum.
7. The method of claim 1 , wherein said antibody binds to a GRK epitope within the amino acid sequence of NSQSYYNGDPFITKDM (residues 182-197 of SEQ ID NO:1).
8. The method of claim 1 , wherein the antibody is a monoclonal antibody.
9. The method of claim 1 , wherein the antibody is a polyclonal antibody.
10. The method of claim 1 , wherein the antibody is a mixture of monospecific antibodies.
11. The method of claim 1 , wherein said determining step is carried out by immunoassay.
12. The method of claim 1 , further comprising determining a level of an inter-alpha inhibitor protein (IaIp) level in said sample, wherein an inverse correlation between an increase in said GRK level and a decrease in IaIp level compared to a normal control indicates a diagnosis of early sepsis.
13. A purified antibody specific for granzyme K protein (GRK), wherein said antibody binds to a GRK epitope within residues 182-197 of SEQ ID NO:1, and wherein said antibody detects free GRK and bound GRK, said bound GRK being a component of a GRK-inhibitor complex.
14. The antibody of claim 13 , wherein said antibody binds to both human and mouse GRK.
15. The antibody of claim 13 , wherein said antibody is an IgG isotype antibody.
16. A purified antibody specific for granzyme K protein (GRK), wherein said antibody binds to a GRK epitope within residues 189-205 of SEQ ID NO:1, and wherein said antibody detects free GRK and bound GRK, said bound GRK being a component of a GRK-inhibitor complex.
17. The antibody of claim 16 , wherein said antibody binds to both human and mouse GRK.
18. The antibody of claim 16 , wherein said antibody is an IgG isotype antibody.
19. A method of making a sepsis-detection reagent comprising immunizing an animal with a purified peptide consisting of a GRK epitope contained in residues 182-205 of SEQ ID NO:1 to generate an antibody, isolating said antibody, and, determining binding of said antibody to a GRK epitope within said residues 182-205 of SEQ ID NO:1, wherein detection of said binding indicates that said isolated antibody comprises a sepsis-detection reagent.