After pathogen recognition and binding, the pathogen is put into a vesicle and brought into a phagocyte (phagocytosis). After the phagocyte is engulfed, lysosomal enzymes digest the pathogen. Reactive oxygen species from respiratory bursts and reactive nitrogen compounds can also degrade pathogens. Waste leftover from degradation is excreted as well as processed by leukocytes. This processing allows key antigens to be presented on the cell surface for adaptive immune responses.