The spleen is an organ found in all vertebrates. It is a large secondary lymphoid organ that primarily functions as a blood filter. The second spleen’s function is immune system surveillance. As a specialized immune organ, the spleen plays a significant role in innate and adaptive immunity. Specifically, the spleen is a crucial organ for peripheral immune tolerance, complementing central immune tolerance. Splenectomy in both study animals and humans results in overwhelming infections with especially, encapsulated bacteria [1]. On the opposite, supporting the immune system with an additional spleen or the substances it produces can help to treat many diseases. In world practice, there are some commercial preparations of the spleen extracts, such as Solkosplen, Splenic, Polygram, Splenopid, Splenaktiv, and others [2] that have been liscensed for use to treat diseases.