Before revision:  In this work we use a combination of statistical physics and dynamical systems approaches , to analyze the  response to an antigen  of a simplified model of the adaptive immune system, which comprises B, T helper and T regulatory lymphocytes.
After revision: Recent experimental studies have suggested the ratio between T-helper and T-suppressor lymphocytes as an index of immunosuppression in HIV, cancer, immunosenescence and inflammatory and auto-immune diseases. However, a quantitative understanding of the impact of this ratio on the immune response has lagged behind data and its validity as a tool for prognostic monitoring or therapeutic target remains an open question. In this work we use a combination of statistical physics and dynamical systems approaches , to analyze the response to an antigen of a simplified model of the adaptive immune system, which comprises B, T helper and T regulatory lymphocytes.