immune system cells. defense viruses macrophage immune monocyte lymphocyte pictures in cartoon style recent set

virus bacterial megakaryocyte plasma immunoglobulin platelet nkcell neutrophil fibroblast immunization shield micro defense cell biology health immune medicine system vector medical human macrophage antibody microbiology organism care icon isolated structure molecule image infect molecular immunity infection physiology bacterium bacteria illustration science set protection antigen design simple anatomy background symbol sign