A Dual-Phase Evolution Model of Emergency Myelopoiesis

The immune system is one of the progressive Complex Adaptive Systems (CASs) that generates cellular response against the foreign disturbances and also exhibits prominent properties such as emergence and self-organization. In a steady state, where a localized infection is caused by the disturbances, the myeloid immune cells are continuously created in the bone marrow. Nevertheless, if the infection gets distributed throughout the body, then these immune cells are created in a larger quantity due to the myelopoiesis process to fulfill the increased demand. This demand leads to the state change in the system from its steady state to the demand adapted emergency myelopoiesis state causing cellular emergence. After the infection, it returns to the steady state due to the self-organization. This immune response results in the phase transitions from steady state to emergency myelopoiesis state and back. Dual-phase evolution (DPE) is a process that brings emergence and self-organization in the CASs due to the phase transitions. DPE allows the immune system to rest in one of the phases such as a steady phase (i.e., the local or poorly connected phase of the DPE) or an emergency phase (i.e., the global phase of the DPE due to the increased number of cells), although it is predominantly the steady phase. In this paper, we propose an integrated model of the emergency myelopoiesis, DPE, and network theory. This model helps to understand the cellular interactions during the phase transitions along with its prominent properties. It is concluded that during the global phase, the immune network exhibits scale-free property. This network further follows the power-law for the degree distribution of its nodes.