Gamma-IFN liquid-droplet aerosol and method

.A liquid-droplet aerosol composition for delivery to a patient's respiratory tract: (a) formed by placing an aqueous gamma-IFN solution having a known, selected gamma-IFN biological activity, and comprising a stabilizing agent and a dispersing agent, against a plate having defined-size openings, and forcing the solution through said openings under conditions effective to form aqueous droplets having: (i) a distribution of size that is less than 2 standard deviations from the volume mean diameter of the droplets, wherein the volume mean diameter is in a selected size range selected from the group consisting of: less than 1 micron; 1-3 microns; 3-5 microns; 5-10 microns; and greater than 10 microns; (ii)' a gamma-IFN biological activity substantially the same as that of the solution; and (iii) a gamma-IFN molecular size distribution substantially the same as that of the solution; and (b) characterized by an aerosol of aqueous droplets having: (i) a distribution of sizes that is less than 2 standard deviations from the volume mean diameter of the droplets, wherein the volume mean diameter is in a selected size range selected from the group consisting of: less than 1 micron; 1-3 microns; 3-5 microns; 5-10 microns; and greater than 10 microns; (ii) a gamma-IFN biological activity substantially the same as that of the solution; and (iii) a gamma-IFN molecular size distribution substantially the same as that of the solution.