This disclosure describes inventions related to the use of biological agents that cause cytokine receptors to be released from the surface of cells. One aspect of this invention is based on the unexpected finding that extending the length of an exemplary agent at the N-terminus enhances expression and production of the product by at least 10-fold. The extended protein can be used to prepare pharmaceutical compositions for treating inflammatory conditions such as rheumatoid arthritis. Another aspect of this invention is based on the identification of biological agents that cause release of cytokine receptors not previously known as natural enzyme targets, such as the IL-1 Type I receptor, IL-1 Type II receptor and the IL-6 receptor. This disclosure provides products, assays, expression systems, purification methods, and production protocols useful for developing cytokine receptor releasing proteins as therapeutic agents.