Lactose and 10 mM PBS were purchased from Sigma Chemical Co. Purified ricin, ricin Achain,
ricin B-chain, and agglutinin (RCA-120) used by the U.S. Food and Drug Administration (FDA) were purchased from Vector Laboratories (Burlingame, CA). Lectins derived from pea (Pisum sativum), peanut (Arachis hypogea), and wheat (Triticum vulgaris) were purchased from Sigma Chemical Co.
(catalog numbers L0881, L5380, and L9640, respectively).