Immune activation with peptide assemblies carrying Lewis y tumor‐associated carbohydrate antigen

Molecular assemblies varying morphologies in a wide range from spherical micelle, nanosheet, curved sheet, nanotube and vesicle were prepared and loaded with Lewis y (Ley) tumor‐associated carbohydrate antigen on the assembly surface. The molecular assemblies were composed of poly(sarcosine)m‐block‐poly(L‐lactic acid)30 (m = 15 or 50, Lactosome), poly(sarcosine)m‐block‐(D/L‐Leu‐Aib)n (m = 22 or 30, n = 6 or 8) and their combinations. The molecular assemblies carrying Ley on the surface were administered in BALB/c nu/nu mice. The major epitopes of the molecular assemblies are commonly Ley and poly(sarcosine). IgM productions upon administrations of the molecular assemblies were assayed by ELISA, showing that anti‐poly(sarcosine) IgM was highly produced by Lactosome of spherical micelle but with a negligible amount of anti‐Ley IgM. On the other hand, the nanosheet of the interdigitated monolayer triggered the production of anti‐Ley IgM but with less anti‐poly(sarcosine) IgM production. Taken together, IgM specificity differs according to the molecular environment of the epitopes in the molecular assemblies. The antigenicity of poly(sarcosine) was augmented in polymeric micelle providing loose environment for B cells to penetrate in, whereas a high density of Ley on the molecular assembly was required for anti‐Ley IgM production. The antigenicity of Ley is therefore dependent on the molecular assemblies on which Ley is displayed on the surface. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Peptide assemblies taking various morphologies were prepared with using amphiphilic block polymers having the same hydrophilic poly(sarcosine) block. Nanosheet carrying Lewis y antigen (Ley) on the surface was found to be the most effective to produce anti‐Ley IgM due to the high density of Ley on the surface. Other peptide assemblies mainly produced anti‐poly(sarcosine) IgM. The results strongly imply that B cells differ in modes to recognize the epitopes in the molecular assemblies.