Cytoagglutination and cytotoxicity of Wheat Germ Agglutinin isolectins against normal lymphocytes and cultured leukemic cell lines -: relationship between structure and biological activity

The relationships between degree of lectin-cell binding, cytotoxicity and cytoagglutinating activity of three Wheat Germ Agglutinin isolectins (WGA-1, WGA-2, WGA-3) against normal lymphocytes and cultured leukemic cell lines (Jurkat, MOLT-4, Raji, Daudi, K-562) were studied. All WGA-isolectins interacted in a similar degree with normal lymphocytes, while in the case of leukemic cells, the degree of isolectin-cell binding increased in the order: WGA-1 less than or equal toWGA-3<WGA-2 at isolectin concentrations 0.5 muM and higher, and WGA-3 < WGA-2 less than or equal to WGA-1 at 0.2 5 muM isolectin concentration. The WGA interacted in higher degree with Jurkat, Raji, Daudi and K-562, followed by MOLT-4 and normal lymphocytes. The velocity of cytoagglutination in the presence of 0.25 muM WGA-isolectins increased in the order: WGA-3 < WGA-2less than or equal toWGA-1, and was better expressed in Jurkat, Raji, Daudi and K-562, followed by MOLT-4 and normal lymphocytes. The cytotoxicity of isolectins was very well expressed against Jurkat, MOLT-4, Raji and Daudi, and less expressed against K-562 and normal lymphocytes. In the case of leukemic cells, the cytotoxic effect of WGA-isolectins increased in the order: WGA-3<WGA-2 = WGA-1. A very good positive correlation was determined between velocity of cytoagglutination and degree of lectin-cell binding (r=0.77, P<0.001). A good inverse correlation was found between cytotoxicity and degree of lectin-cell binding (r=- 0.34, P<0.001), and poor correlation was observed between cytotoxicity and cytoagglutinating activity of WGA-isolectins (r=0.16, P<0.01). The results suggest that the WGA-isolectins, structurally distinguishable in only several amino acid sequences, interacted in different degrees with leukemic cells and manifested different cytoagglutinating and cytotoxic activity. (C) 2002 Elsevier Science B.V All rights reserved.