t cell activation diagram, t lymphocytes, helper t-cell and cytotoxic t-cell , white blood cells

diagram presentation lymphocyte helper t-cell cytotoxic vector scheme white blood cells immune response infection responses apoptosis lymphocytes adaptive memory system biology antibodies antigen presenting cytokines killer receptor b-cell pathogens antibody activation regulate produce perforin granzymes enter target infected lead infection virus lymphocyte science immune system cell