Peanut Agglutinin (PNA), Unconjugated, 5 mg. PNA binds preferentially to the T-antigen, a galactosyl (β-1,3) N-acetylgalactosamine structure present in many glycoconjugates. PNA is useful in distinguishing between normal and tumor tissues, in assessing malignancy in transitional mucosa, and in fractionating stem cells in mice for use in bone marrow transplantation across histocompatibility barriers. PNA binding can also be used to measure cellular maturity in lymphoid tissues, to distinguish a variety of lymphocyte subpopulations, and to measure the levels of lymphoid cell populations in many diseases. With certain exceptions, the receptor sequence for PNA is normally sialylated which prevents the lectin from binding to its receptor oligosaccharide. Even sialic acid which is not bound directly to the receptor sugars may inhibit binding. The presence of calcium ions in diluents can enhance the binding of PNA to receptors.