[Resistance to infection. Physiology and pathology of the immune system].

The contribution of observations in congenital deficiency disorders to our understanding of normal mechanisms can hardly be overestimated, as may in particular be seen in the complex field of mechanisms aiming at maintaining the individual integrity. After a brief summary of the natural lines of defense we demonstrate a few cases with typical deficiencies, i.e. of the integuments (ciliary dyskinesia syndrome), of the phagocytes (chronic granulomatous disease = CGD), of specific immune reactions (antibody deficiency syndrome, severe combined immunodeficiency = SCID and syndromes with associated immunodeficiencies), and finally of the complement properdin system. Classification of these Primary Immunodeficiency Syndromes (= PIDS) with exceptional research potential as proposed by an expert panel of the WHO turned out to be quite useful also for the understanding of by far more frequent secondary disorders, in particular of the recently observed acquired immunodeficiency syndrome = AIDS due to an infection with the human immunodeficiency virus (= HIV). For pediatricians in industrialized countries, however, children with frequently recurring, but trivial infections are of considerable practical importance. A clear diagnostic concept is the necessary base for the proposed treatment, counselling and help for the inflicted parents.