Model-based analysis of CD4+ lymphocyte dynamics in HIV-infected individuals. II. Evaluation of the model based on clinical observations

A mathematical model and CD4+ lymphocyte dynamics in HIV infection

The paper presents a model of CD4 + lymphocyte dynamics in HIV-infected persons. The model incorporates a feedback mechanism regulating the production of T lymphocytes and simulates the dynamics of CD8 + lymphocytes, whose production is assumed to be closely linked to that of CD4 + cells. Because CD4 + lymphocyte counts are a good prognostic indicator of HIV infection, the model was used to simulate such therapeutic interventions as chemotherapy and active and passive immunization. The model also simulated the therapeutic administration of anti-CD8 antibodies; this intervention was assumed to activate T-cell production by activating a feedback mechanism blocked by the high numbers of CD8 + lymphocytes present in HIV-infected persons. The character and implications of the model are discussed in the context of other mathematical models used in HIV infection.

Mathematical modelling of HIV infection therapy

The previously developed mathematical model simulates the CD4+ lymphocyte dynamics in HIV infection very well. As the number of these cells is a good indicator of the infection progression, it was used to evaluate the effectiveness of different therapeutic interventions. For chemotherapy simulation, both permanent and temporary zinovudine (AZT) administration were considered and the induced return of the CD4+ lymphocyte counts was analysed. Similar analysis was performed for active and passive immunotherapy. The model offers also the possibility of stimulating the CD4+ dynamics after depletion of CD8+ lymphocytes by antibodies. Even one simulated administration of anti-CD8 antibodies increases the CD4+ lymphocyte counts and prolongs the survival of the patient. However, if cells involved in protective immunity are assumed to belong to the CD8+ category, anti-CD8 antibodies accelerate the decrease of CD4- cells and thus shorten the patient's survival.