Synthetic polymers, immune response

Mosbach and collaborators, in 2001, described an innovative approach to drug discovery using polymers imprinted with a biologically active template [31]. The approach, called anti-idiotypic for the similarity with anti-idiotypic antibodies in the immune-response, can be used to create synthetic receptors able to generate inhibitors or receptor antagonists by exploiting the complementarity with the cavity. The imprinted cavity promotes preferentially the formation of compounds with high affinity, which can later be evaluated for the inhibitory activity and the more active selected for further analysis. 

Besides the many immunological events that can be initiated by the synthetic polymers as just described, there are also the pathological implications to be considered, such as the in vivo fate of the Ag-Ab complexes. Consequently, there is an urgent need for emphasis on immunological studies of biomaterials. Meanwhile, from our data and the information in the literature as just described, it appears that artificial organs may not be immune to immune responses. But the long-term effects of such responses as well as these effects on the complement system seem to be much more complex than are realized at present. 

It is a common practice to use adjuvants mixed with the antigen to help boost immune response by slow release of the antigen, which leads to extended exposure of the immune system to the antigen. The most common adjuvants used for the production of antibodies are complete (CFA) and incomplete (IFA) Freund s adjuvant. Both are a combination of water-in-oil emulsions and a surfactant, but they differ in the presence of killed mycobacterium in the complete formula. Because of potential side effects of CFA, its use is limited to the first immunization, and booster doses are applied in IFA. Other adjuvants used are aluminum salts and synthetic polymers, but in our experience they are not as effective as CFA and IFA. We have found that by choosing the amount of inoculum and route of immunization carefully, most adverse side effects of CFA use can be minimized or avoided. 

Thomasin C, Corradin G, Ying M. Tetanus toxoid and synthetic malaria antigen containing poly(lactide)/poly (lactide-co-glycolide) microspheres importance of polymer degradation and antigen release for immune response. J Control Release 1996 41 131-45. 

The use of chemically defined synthetic polymers is associated with minimal human immune responses. These materials are based on carbon, hydrogen, nitrogen and oxygen which are basic building blocks of the biological system. Thus the generation of antigenic material would be unlikely. Nevertheless, there are some polymeric materials with additional chemical moieties that are of concern. 

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