A rapid qualitative method to assess in vitro immunobarrier competence of pancreatic islets containing alginate/polyaminoacidic microcapsules.

A quick method for the qualitative evaluation of immunoisolatory properties associated with islet-containing alginate/poly-L-ornithine (AG/PLO) microcapsules is described. In particular, we examined a new AG/PLO coherent microcapsule (CM) prototype that was recently developed in our laboratory, although the procedure could be applicable to other capsule types as well. We observed no binding of immunoglobulins (Ig) contained in islet cell antibody (ICA)-positive human sera (> 60 Juvenile Diabetes Foundation units, JDT U) to pig islets, enveloped within AG/PLO CM, under indirect immunofluorescence examination. Also, CM were shown to inhibit human lymphocyte proliferative capacity fully, as assessed by the 3H-thymidine incorporation rate, in in vitro mixed xenogeneic pig islet/human lymphocyte co-cultures. These results provided us with a preliminary method to attempt standardization of basic physical/chemical properties which should be associated with an immunoisolatory membrane for islet allo/xenograft immunoprotection.