  There is little research concerning comparisons and combination of System
Dynamics Simulation (SDS) and Agent Based Simulation (ABS). ABS is a paradigm
used in many levels of abstraction, including those levels covered by SDS. We
believe that the establishment of frameworks for the choice between these two
simulation approaches would contribute to the simulation research. Hence, our
work aims for the establishment of directions for the choice between SDS and
ABS approaches for immune system-related problems. Previously, we compared the
use of ABS and SDS for modelling agents' behaviour in an environment with
nomovement or interactions between these agents. We concluded that for these
types of agents it is preferable to use SDS, as it takes up less computational
resources and produces the same results as those obtained by the ABS model. In
order to move this research forward, our next research question is: if we
introduce interactions between these agents will SDS still be the most
appropriate paradigm to be used? To answer this question for immune system
simulation problems, we will use, as case studies, models involving
interactions between tumour cells and immune effector cells. Experiments show
that there are cases where SDS and ABS can not be used interchangeably, and
therefore, their comparison is not straightforward.
