Normal functions of the spleen relative to red blood cells: a review.

By Wau i H. CROSBY I HE WORDS hyposplenism and hypersplenism have enjoyed a long vogue. Hyposplenism, which may have been used first by Eppinger in 1913,1 has come to mean a pattern of changes that are due to or related to absence or atrophy of the spleen. Hypersplenism, coined by Chauffard in 1907,2 is more commonly used, but it describes a condition that is considerably less well defined. Hyperspienism is usually intended to mean a pathologic exuberance of splenic function which is manifested by a lack of circulating blood cells. Hyperspienism is usually associated with splenomegaly, but it is not essential that it be. The mark sterling of the hyperspienic syndrome is cure by removal of the spleen.3 Hyposplenism and hypersplenism describe the spleen’s errors of omission and errors of commission. Now a word is needed to describe the honest, daily toil of a healthy spleen in a healthy body. The word “splenism” was introduced into the hematologists’ vocabulary by Dameshek4 who said that it means “normal functional activity of the spleen,” but he has added, with characteristic caution, that it is not definitely known whether splenism exists. However, for purposes of discussion let us assume that the spleen has normal functions, that certain of these functions pertain to the erythrocytes, and that some of the normal functions of the spleen may involve abnormal situations. For example, when the spleen is torn it may heal itself. The injury is abnormal, but healing is a normal function. When pathogenic bacteria or abnormal red cells appear in the splenic pulp, the spleen may destroy them-a normal splenic function. This short discussion will restrict itself to those normal splenic functions which relate to the erythrocyte: splenism and the red cell. Of the methods used to study splenic function, splenectomy probably heads the list. Ligation of splenic blood vessels also has been used and spleens have been transplanted with and without maintaining the integrity of the blood supply. Parabiosis has been used, joining the circulations of a splenectomized animal with one whose spleen is intact. Other technics have been tried, too numerous to mention. In this field of splenic function, as in every other, there are pitfalls set and waiting. For years the results of splenectomy in dogs were distorted by the presence of unsuspected bartonella infections which caused hemolytic disease when the protecting spleen was gone.5 Experiments with parabiotic rats have been interpreted upon the assumption that blood cells are not exchanged by parabionts,6 but actually two-thirds