The immune system is a collection of billions of cells that travel through the bloodstream. They move in and out of tissues and organs, defending the body against foreign bodies (antigens), such as bacteria, viruses and cancerous cells.There are two types of lymphocytes :B cells-produce antibodies which are released into the fluid surrounding the bodyâs cells to destroy the invading viruses and bacteria. T cells (see picture opposite) - if the invader gets inside a cell, these (T cells) lock on to the infected cell, multiply and destroy it.here are two types of lymphocytes : B cells-produce antibodies which are released into the fluid surrounding the bodyâs cells to destroy the invading viruses and bacteria. T cells (see picture opposite) - if the invader gets inside a cell, these (T cells) lock on to the infected cell, multiply and destroy it.
Gillespieâs algorithm (Gillespie, 1977) is a way of im-. plementing consistently this probabilistic description of a biological system. The probabilistic. description by its very nature applies to single cells. The connection with molecular concentra-.
Largo B. Pontecorvo 3, 56127 - Pisa, Italy. {barbuti,maggiolo,milazzo,troina}@di.unipi.it. Abstract. We introduce a probabilistic algorithm for the simulation. of chemical reactions, which can be used as an alternative to the well-. established stochastic algorithm proposed by D.T. Gillespie in the â70s. We show that the probabilistic evolution of systems derived by means. of our algorithm can be compared to the stochastic time evolution of. chemical reactive systems described by Gillespie. Moreover, we use our. algorithm in the deï¬nition of a formal model based on multiset rewriting,