The present invention relates to using lectin or lectin-like molecules to promote oligomerization of a glycoprotein or an immunologically and/or biologically active complex comprising glycoproteins. In particular, the invention provides compositions of a molecular complex comprising lectin molecules and immunologically and/or biologically active molecules. Methods of making such molecular complexes and methods of use of the compositions comprising such molecular complexes for the prevention and treatment of diseases, particularly cancer and infectious diseases, and for eliciting an immune response in a subject, are also provided.