In the postgenomic era, interactions between organism and environment are central in disciplines such as epigenetics, medical physiology, and immunology. Particularly in the more "applied" medical fields, an emphasis lies on interactions of the organism with other organisms, that is, other living things. There is, however, a growing amount of research investigating the impact of abiotic triggers on the immune system. While the distinction between biota and abiota features heavily in other contexts, its status is not explicit within immunology. Do (...) immunologists distinguish living from nonliving triggers? In this article, I will carve out whether and in which ways the biotic/abiotic distinction operates in immunology. I will look into responses to biotic and abiotic stressors in plant and invertebrate model species and ask how and why they are conceptually separated. I will trace the reasons by investigating the disciplinary situatedness of immune phenomena and the import of vertebrate immunology when conceptualizing immune responses in other model organisms. I will then investigate how the convergence of biotic and abiotic stress responses in plants and invertebrates adds to the recent philosophical programs advocating an ecological perspective on immune systems. (shrink)