ABSTRACT
In his chapter on the history of the Wassermann reaction, Ludwik Fleck criticized the dominant perception of immune reactions as explained in Julius Citron’s classical text. For Citron, immunity was the specific reaction of a well-defined, closed unit – the organism – to invading pathogens.1 ere was an unambiguous external cause – attack – and a precise reaction – defense. He depicted the resulting conflict between body and invading pathogen as the essence of disease. Such a view of immunity, Fleck argued, drastically oversimplified host-pathogen interaction:
In addition, serogenesis and immunogenesis were not merely reactions to pathogenic microorganisms: these were fundamental biological mechanisms, and were therefore the result of reciprocal changes within the complex life unit. For Fleck, interaction between host and parasites should not be conceptualized in terms of ‘attack’ and ‘defense’, but should be seen as a biological process, akin to development, ageing, or cyclic fluctuations in life cycles of parasites and bacteria.3
