The present invention discloses soluble isoforms of CD5 and CD6, which are scavenger-like lymphocyte receptors, for use in the prophylaxis or therapy of disorders or in therapeutic interventions, which would benefit from an exacerbated immune response to either endogenous or exogenous antigens, resulting from a decrease in lymphocyte subpopulations with regulatory functions and/or increase in lymphocyte subpopulations with effector functions. Special disorders are cell growth disorders, and chronic infections of bacterial, viral, fungal or parasitic origin. The invention also provides animal models for the study and the prophylaxis/treatment of autoimmune diseases, cancer, and chronic infections.
