The nature of neutral red staining refractive particles in the lymphocytes of the blood of normal humans.

Louis H. HEMPELMANN, M.D. AND NORMAN P. KNOWLTON, Ju., M.D. T HE EXISTENCE of neutral red staining refractive cytoplasmic particles in the lymphocytes of normal humani peripheral blood has been knownn since their (lescriptiomi by Gall’ inn 1936. These particles earn be distinguished from nonrefractive cytoplasmie vacuoles which also stainn with neutral red dye. Several observers in this laboratory have reported that the lymphocytic particles,* as seem inn the supravitally stained preparations of blood, are increased numerically under eertaimn eonditionns.2’ Thus, there are more refractive particles inn the lymphocytes of pen’somns exposed either to total body ionizing radiation or to certainn toxic chemicals than there are in the lymphocytes of unexposed persons. This change does riot provide the basis for a practical test of excessive radiation exposure as it appears to be nonspecific. Furthermore, its method of study is tedious amid tends to be subjective. Also, the sigmiificannce of am increase inn refractive 1)odies is not clear, amid its relationship to tissue damage is not understood. The imnterpretationi of this morphologic chamnge inn lymphocytes has been made more difficult by a recent report5 that the number of particles in unistained lympinocytes is not increased inn persons receiving large doses of radioiodine. The present paper presents the results of ann investigation unto the nature of the lymphocytic granules.