 Different models of epistemic reduction have been considered with little consensus about the applicability of this type of explanation (Sarkar 1998). Dissatisfaction with models of theory reduction led to various models of explanatory reduction that, unlike deductive-nomological accounts, consider relationships between epistemic units other than theories containing laws, while relying on an intuitive sense of reduction as an explanation of higher level features in terms of their parts (see the entry on  reductionism in biology).  A dominant concern about reduction is the so called “many-many” relationships between levels of analysis, where biological features are context dependent and may vary due to heterogeneous lower level features (Hull 1974; Fodor 1974; S. Gilbert and Sarkar 2000). One approach maintains that non-reductionist explanations should focus on gross “cytological” features of the studied phenomena rather than on lower level molecular processes (Kitcher 1984). In contrast to this approach, immunologists assume that reduction is an attempt to explain complex immune phenomena in terms of isolated parts and interactions without taking into consideration the entirety of structural and functional complexities (Van Regenmortel 2002). Thus, instead of assuming that non-reductionist explanations must ignore lower level molecular details, holistic immunologists attempt to understand the multilevel complexity of the immune phenomena they study (Rivas et al. 2017). Accordingly, non-reductionist descriptions do not attempt to remain on a descriptive, biological level of understanding, but rather adapt pluralistic approaches that integrate distinct dimensions and frames of reference, i.e., both molecular and higher orders of analysis. This perspective aligns with recent approaches in philosophy of biology that move beyond the division of lower- and higher-level explanatory strategies and highlight the importance of interdisciplinary integration exhibited by current scientific practice (Brigandt 2010; Love and Lugar 2013).