[Role of the spleen in immunity. Immunologic consequences of splenectomy]

The spleen is a lymphatic organ that plays a fundamental role in protecting the body from invading pathogens. Being an organ that is interposed in the blood stream, it also stands as the body's largest blood filter that furthermore brings contribution to detecting senescent, mechanically damaged and aberrant cells. The spleen combines the innate and adaptive immune system in a unique way, releasing an immediate innate reaction to microbial penetration, but also an adaptive immune response that involves the interaction of cells that recognize a particular antigen, implicating MHC molecules presented by antigen-presenting cells. Clinical manifestations of some hematologic conditions can be controlled by splenectomy. The use of this procedure, although, has been restricted due to many observations of overwhelming post-splenectomy bacterial infections in splenectomized patients. After splenectomy, the mechanisms that play a fundamental role in bacterial clearance are altered, leading to gram-positive, but also gram-negative sepsis. Subtotal splenectomy is, therefore, a logical alternative that controls the manifestations of hematologic diseases while maintaining splenic function.