Systems and System Models

In this modeling exercise, students examine scientific data on HIV immunity to explore the cross-cutting concept “System and System Models”.

This modeling exercise is focused on the initial work of Paxton et al (1996). This looks at the potential that some individuals might be resistant or immune to HIV. HIV serves as the phenomena for this exercise and students should know the basics on how HIV works before attempting it. In this exercise the interactions between HIV, Helper T Cells, and Killer T Cells are the system. Introduce students to the general models that are used in Paxton et al.’s Fig 1 on the board. Then ask students to model how p24 levels might change over time in the blood of someone that has Helper T cells versus Helper T Cells and Killer T cells. Once students have modeled this, they can compare their models to those of Fig. 1a to look at actual data for comparison. Then more modeling can be conducted for students to hypothesize how the graph might be different for those that are resistant to HIV before they compare this to Fig. 1b. This modeling exercise works well for exploring systems given the complexity of immune response and how HIV interacts with it. Paxton, W. A., Martin, S. R., Tse, D., O'Brien, T. R., Skurnick, J., Van Devanter, N. L., ... & Koup, R. A. (1996). Nature medicine, 2(4), 412-417.

Suggested Modeling Elements: Cells: Blood Cells

Suggested Sensemaking Components: Movement/Motion, Flow of Matter, Zoom in/out