Levels of APRIL in serum and use in diagnostic methods
The present invention provides a method of measuring the levels of APRIL in a biological sample, in a preferred embodiment, in serum. The diagnostic assays are useful in predicting an individual's likelihood of developing or currently suffering from an autoimmune disease, such as RA, predicting the future severity of the disease, and for methods for treating an individual clinically diagnosed with an autoimmune disease. This diagnostic test serves to predict a patient's likelihood to respond to a specific drug treatment, in particular treatment with APRIL antagonists, either singly or in combination with other immune suppressive drugs.
1. A method of detecting increased A Proliferation-Inducing Ligand (APRIL) protein expression of an individual at an early stage of rheumatoid arthritis (RA) comprising:
(a) measuring a first level of APRIL protein expression in a biological sample of said individual;
(b) comparing that level to a second level of APRIL protein expression in a biological sample of a healthy control; and
(c) determining whether the first level is increased as compared to the second level,
wherein said increased APRIL protein expression is associated with an early stage of RA.
2. An in vitro method of detecting increased APRIL protein expression in the serum of an individual at an early stage of rheumatoid arthritis (RA), comprising:
(a) measuring the level of APRIL protein expression in a test serum sample from the individual;
(b) comparing that level to the level of APRIL protein expression in a serum sample from a healthy control; and
(c) determining whether the level of APRIL protein expression in the test serum sample is increased as compared to the level in the control sample;
wherein said increased APRIL protein expression is associated with an early stage of RA.
3. The method of claim 1 , wherein the biological sample is synovial fluid.
4. The method of claim 1 , wherein the biological sample is serum.