Immunopathogenic mechanisms in tissue damage

Our knowledge on immunopathogenic damage is derived from multiple different sources: experiments in vitro, experiments in vivo, clinical observations, and observations using material from multiple different animal species including man. If we want to analyse an immunological process suspected of causing tissue damage we have critically to evaluate the mechanism of immunologically specific initiating factors and the mechanisms of non-specific mediating factors. It is necessary to have clear information on the identity of the antigen, the location of the antigen, the identity of antibody, the location of antibody and similar information on specifically reactive lymphocytes. With this information in mind it is possible to hypothesize upon mechanisms, which can be responsible for the immunologically specific initiation of immuno-pathogenic damage. The non-specific mediating systems, which are the actual inducers of functional or structural tissue damage, are triggered by the specific, initial immune reaction. These systems comprise for instance complement, coagulation, granulocyte and macrophage lysozomes and function, chemotaxis, the mast cell system, phagocytosis etc. The overall picture of non-specific mediation of tissue damage is extremely complex, since it really makes it necessary to investigate and describe not only these systems but also their co-existence and interaction. Knowledge of immunopathogenic mechanisms in clinical disorders in man is still resting mainly upon analogies and assumptions, although progress is taking place. It is essential to ask the right questions and critically to evaluate the answers. Thereby the understanding of immunopathogenesis in diabetes mellitus and other clinical disorders shall gradually improve.