Metaphors are a crucial factor in students’ biological content learning as they are used to make abstract phenomena more comprehensible. Therefore, metaphors are used in biology education to support students’ learning. However, metaphors might even impede the understanding of non-native speakers: They must not be understood literally, but in a transferred sense, and the usage of metaphors differs between different languages as well as cultures. So far, it is still unclear what impact different first languages have on students’ use of metaphors with respect to their biological content learning. This study examines which metaphors students with different first languages use when talking about immunology as biological phenomenon and to what extent and kind the metaphors differ. For this purpose, guided interviews with 10th grade students (15-17 years old) were conducted. Additionally, information about students’ language biography was collected. The interviews are analyzed by using a combination of two methods: First, Qualitative Content Analysis is used to structure the content of the interviews, and afterwards, the data was analyzed by Systematic Metaphor Analysis to get a deeper insight into students’ metaphor use while talking about different aspects of the phenomenon. Using these methods, a deeper insight into the connection between content and language was gained. Results show that students' use of metaphors differs individually. Contradictory to the state of research, 18 different types of metaphors were found, of which some metaphors were used just by single students.