C. R. Sipe

LYMPHOCYTE PRODUCTION MEASURED BY EXTRACORPOREAL IRRADIATION, CANNULATION, AND LABELING TECHNIQUES*

The lymphatic system has, truly an ancient history that is ably reviewed in Yoffey and Courtice.’ Apparently lymphatics were first observed around 300 B. C. In the 1600s, mesenteric lymphatic vessels and the thoracic duct were described. The classical injection of lymphatic vessels throughout the body by the Hunter Brothers in the 1700s are common knowledge. In 1800, Ludwig commenced cannulation of different lymphatic vessels. In 1851, lymphocytes were first seen within the lymph by Virchow.2 In 1875, Fleming observed mitoses in the germinal centers of lymph nodes. In the late 1800s, Ernest Starling pointed out that lyrnphatic vessels serve as a mechanism by which protein lost from the blood vessels can be returned to the blood. He thus firmly established one major function of the lymphatic system. In this century, a vast literature has developed on the lyrnphopoietic system that is too unwieldly to review in this brief paper. In Yoffey and Courtice’s book on lymphoid tissue, a large mass of the current literature is analyzed. A variation in the concentration of lymphocytes in afferent and efferent lymph has been presented by E h r i ~ h . ~ Following prolonged antigenic stimulus, the output of lymphocytes in the efferent lymphatic ducts of lymph nodes was greatly increased. There is also an increase in the lymphocytes in the lymph while passing through a lymph node. Drinker and Yoffey4 point out that this can not be explained by reabsorption of water in the node because the protein content of peripheal and central lymph is identical in amount. In fact, “if the blood capillaries of the lymph nodes are capable of large scale absorption of protein, they are not only unique members of the blood capillary system, but at the same time display a miraculous ability to absorb proteins so equally as to make afferent and efferent lymph precisely equal in protein content.” Much valuable information had been obtained by cannulation techniques. However, it was with the development of radioactive labels of DNA to tag the new cell production that knowledge on the magnitude of cell production and lifespan of cells began to grow. Again the literature is too large to review in detail. However, the classical studies of O ~ g o o d , ~ Otteson,6 and Hamilton’ are pertinent. Hamilton, utilizing C14-labeled adenine and guanine precursors of DNA, extended Otteson’s ideas on the possibility of two types of lymphocytes ( 1 ) one cell with a long lifespan and (2) another cell with a short lifespan. Alternatively, he could explain his data on the basis that there may be significant reutilization of the labeled DNA or its fragments. Hamilton also first pondered the possible significance of DNA reutilization in perpetuating immune responses. Gowans et ~ l . , * . ~ in a series of precise studies, has pointed out by utilizing classical cannulation techniques, radioactive labeling, and autoradiography that there is a significant recirculation of lymphocytes from blood to the lymphocytic organs and back to the blood again. His group has also confirmed the earlier

Increased Tolerance of Mice to Lethal X-Radiation as a Result of Previous Sublethal Exposures.

Summary and Conclusion 1. It has been demonstrated with a fair degree of certainty (0.05 > Pdiff > 0.02) that three weekly exposures of 144 r followed by a 30 day rest period increases the resistance of mice to a subsequent lethal dose of x-radiation. 2. It is concluded that no adequate explanation for this phenomenon of increased tolerance to x-ray radiation is available at the present time.

STUDIES ON THE APPLICATION OF THE COULTER ELECTRONIC COUNTER IN ENUMERATION OF PLATELETS

The use of the Coulter Blood Cell Counter for counting of platelets in the blood is discussed. Threshold settings for counting separated platelets were determined and coincidence error was calculated. A method was developed for separation of platelets from red cells. Anticoagulant fixatives were developed that prevented adhesion and fragmentation of the platelets. A practical clinical method for platelet counting is outlined. (M.C.G.)

Studies on Lymphopoiesis. VII. Size Distribution of Bovine Thoracic Duct Lymphocytes.

Summary Size distribution studies based upon cell volumes of pure thoracic duct lymphocytes of normal young calves indicate the existence of two populations of cells and delineate the size and range of each.

Failure of rutin to decrease the mortality of acute ionizing radiation illness in mice.

Summary and Conclusions 1. Rutin not only was of no value in improving the survival of mice simultaneously exposed to a dose of ionizing radiation in the lethal range, but significantly increased the rate at which the mice died. 2. It is considered desirable to repeat this type of investigation on animals with ascorbic acid requirements similar to man.

Quantitation of human T-lymphocytes in blood: use of automatic smearing instrument for preparing fixed slides of E-rosettes.

Summary Human T-lymphocytes were enumerated in 10 normal volunteers and 4 pateints by a new method utilizing an automatic smearing instrument to prepare permanent fixed slides of E-rosettes. The results were compared to the commonly employed hemocytometer method. Results obtained smearing instrument were similar to those obtained by the hemocytometer method with the added advantages of permanent record, convenience of quantitation, and precise morphological identification of rosette-forming cells. As opposed to well-preserved E-rosettes obtained by the automatic smearing instrument, hand-made smears showed disruption of E-rosettes.