Comparative analysis of inflammatory infiltrates in collagen-induced arthritis, kidney graft rejection and delayed-type hypersensitivity in non-human primates

Objectives Non-human primates are immunologically closely related to humans providing relevant models of inflammatory disorders often used to evaluate new immunomodulating therapies. The aim of the study was to compare inflammatory infiltrates of acute graft rejection (AR) and collagen-induced arthritis (CIA) to delayed-type hypersensitivity (DTH) reactions as the latter model may serve as a less invasive animal model. Materials and methods Tissue samples of AR, CIA and DTH were obtained from rhesus monkeys used in several pre-clinical studies. The infiltrate composition was determined by immunohistochemical analysis. Results The infiltrates in AR consisted of T cells, macrophages and B cells. The presence of lymphoid structures in AR suggested ongoing intragraft immune activation. The synovia of CIA contained predominantly macrophages and few T cells. The DTH infiltrates were dominated by T cells when the challenged was ovalbumin (OVA) and by macrophages when the challenge was tetanus toxoid (TT). Conclusions The histology of AR resembles aspects of DTH to OVA while that of CIA showed similarities of the DTH to TT. The DTH reaction could serve as a model to study immunomodulating drugs for acute rejection and the acute inflammatory phase of autoimmunity.