The American Reticuloendothelial Society in cooperation with the European and Japanese Societies proposes to hold the IX International RES Congress in Davos, Switzerland, February 8-12, 1982 emphasizing macrophage and NK cell Regulation and function. This application seeks financial support for this Congress to (a) defray costs of invited U.S. participants who have been selected to present either a major address or participate in a major or minisymposium, (b) to assist in certain specific expenses concerned with the organization of the Congress, and (c) to assist qualified U.S. scientists to participate in the Congress by awarding of travel grants that will defray partially the costs of their participation. It is estimated that a total of $52,000 will be required for a one-year period beginning July, 1981.