Production of cultured human mast cells and basophils for high throughput small molecule drug discovery

Patent Number: 7070996

This is a patent covering the use of CD34+ generated mast cells for drug screening. Since technologies for generating mast cells existed in the prior art (for example, as early as 1991 it was known that CD34+ cells can differentiate into mast cells: Kirshenbaum AS, et al. Demonstration of the origin of human mast cells from CD34+ bone marrow progenitor cells. J Immunol. 1991 Mar 1;146(5):1410-5), as well as the concept of drug screening, this invention seems to be a classical "combination patent" (May be in some way similar to that invalidated in Sakraida, but said not to exist in Stratoflex, Inc. v. Aeroquip Corp). In any case, the invention has 1 independent claim that covers "A method of generating cultured mast cells, comprising the steps of: (a) contacting at least one CD34-positive cell with a flt-3 ligand and stem cell factor to generate a proliferated population of progenitor cells; and thereafter (b) contacting said progenitor cells with said stem cell factor and a cytokine suitable for differentiating the progenitor cells into mast cells, thereby forming a proliferated population of mast cells". So interestingly, it is actually not a combination patent, despite its title, but actually just a patent for a specific way of generating mast cells!

View this patent on the USPTO website.