Erythrocyte: Bacteria killer and bacteria pray

Erythrocyte is human blood main bactericidal cell. During movement in blood stream erythrocytes are triboelectrically charged by rubbing to each other and vessel walls and this charge automatically attracts and keeps bacteria on erythrocyte surface. Bacteria fixation on erythrocyte membrane activates the receptors of the membrane and stimulates trans membrane releasing of oxygen from oxyhemoglobin that causes bacteria oxidation and killing. If bacteria survive oxidation and enter erythrocyte they are exposed to higher concentration of oxygen (oxygen reactive species). Very few bacteria survive inside erythrocytes, but some can survive because of lack of oxygen inside erythrocyte and/or bacteria resistance to oxygen reactive species. Killed inside erythrocyte bacteria are released back to plasma and are digested in liver and spleen by local macrophages. Erythrocytes that are injured by bacteria and/or contain killed or living bacteria are destroyed in spleen. Erythrocytes out of bloodstream (in case of hemorrhage, extravasation in lobar pneumonia, etc.) after bacteria engulfment can’t kill bacteria because of lack of oxyhemoglobin and become bacteria container providing both nutrients (protein, iron, carbohydrates, etc.) for bacteria growth and some defense against phagocytes and antibodies. In bloodstream erythrocyte is bacteria killer, out of bloodstream it is bacteria pray.