After continuous H-TdR infusion in vivo or incubation with H-TdR in vitro human blood lymphocytes were examined by light-microscopic and electron-microscopic autoradiography. Using relatively long autoradiographic exposure times (50-300 days) not only nuclear but also cytoplasmic labelling was visualized, the cytoplasmic label being present in up to 96 % of the cells. The cytoplasmic label was predominantly associated with the mitochondria and was removed from the cells nearly completely by treatment with DNase but not with RNase or cold perchloric acid. It is concluded that this cytoplasmic label mainly represents H-TdR incorporated into mitochondrial DNA which is continuously renewed in an average turnover time of 14 days or less. This value is compatible with a turnover time of 11 days for mitochondrial DNA in mammalian cells reported in the literature.

Neuere Untersuchungen über die Kinetik der Lymphocyten deuteten darauf hin, daß die überfüllung des Organismus mit Lymphocyten bei der chronischen lymphatischen Leukämie nicht durch eine beschleunigte Neubildung, sondern vielmehr durch eine verlängerte Lebensdauer dieser Zellen hervorgerufen wird. Daher wurden Maßnahmen gesucht, die Lymphocyten selektiv zu zerstören.

Berlin, Heidelberg, New York, London, Paris, Tokyo, Hong Kong: Springer-Verlag Philadelphia, Pennsylvania

More importance is being attached to haematologic cell morphology, particularly in the field of small-cell non-Hodgkin lymphomas. This shifting of diagnostical validity from the structural substrate to the cellular one can clearly be illustrated by the transition of classification according to Rappoport to that according to Lennert (Kiel-classification). Here minute cytomorphological criteria acquire a new validity by their significance in the microscopic cut preparation and in the electron-microscope as well as by their correlation to cell-immunological parameters. Thus, it is possible to make a differential diagnostics of the extending small-cell lymphomas from the blood picture. It enables an ensured morphological differentiation to be made for typical B-lymphadenosis, prolymphocytic leukaemia, T-cell lymphadenosis, lymphoplasmocytoid immunocytoma, centrocytoma, and hairy cell leukaemia. The relevance of this differentiation can be further identified by a consequent immunologic cell characterization.

Two hematologically normal patients with glioblastoma and six patients with chronic lymphocytic leukemia received continuous3H-thymidine infusions for 3–10 days. In autoradiographs of blood cell smears taken for 25 days or more after the beginning of3H-thymidine administration the labeling index and the labeling intensity of granulocytes were determined. A sufficiently high labeling intensity, i. e. a sufficiently long autoradiographic exposure time was found to be critical for obtaining valid and reproducible results. On the basis of certain assumptions discussed in detail, complete labeling of cells with3H-thymidine followed by autoradiographic evaluation and mathematical analysis of the labeling patterns seems to be a suitable method for estimation of kinetic parameters of postmitotic granulocytes in vivo.

In 21 patients with chronic lymphocytic leukemia (CLL) and in 8 hematologically normal persons the number of DNA-synthesizing peripheral blood lymphocytes was investigated by autoradiographic techniques. The lymphocytes were differentiated by En-rosette tests into T and non-T lymphoid cells. The results show a normal number of proliferating T lymphoid cells and an increased number of proliferating non-T lymphoid cells in clinical stages O-I. Stages III–IV demonstrate a significant increase of the proliferation rate of both T and non-T lymphoid cells. The possible pathogenetic factors and the prognostic value of these results are discussed.

Untreated malignant lymphatic system diseases are characterized by a preponderance of cell new formation (proliferation) against the destruction of lymphatic cells. If the lymph nodes are enlarged during these diseases, then cell new formation occurs largely or mostly in these lymph nodes. The proliferating cells of the lymph node are bigger than small lyphocytes and have, in general, a mean diameter of the nucleus of 10 mu and more. In normal lymph nodes they belong morphologically to the big lymphocytes, immunoblasts and plasmoblasts. In pathological lymph nodes they have to be looked for among the bigger cells of the disease-specific cell population. Whereas in healthy lymph nodes and in chronic lymphatic leukemia only about 1% of lymph node cells was found to proliferate, they amount on the average to 5% in lymphomas of lymphogranulomatosis and mostly to 30--50% in the lympho-reticulosarcoma (lymphoblast and immunoblast sarcoma, corresponding to large-cell, poorly differentiated lymphomas). The proliferating cells often appear as foci in the lymphomas. The generation times of the proliferating cells both in normal and pathological lymph nodes are about 24 hrs. or slightly longer. In lymphatic proliferation, apart from plasma cells big and smallymphocytes are produced in the normal lymph node; in CLL, big and small lymphocytes, in lymphogranulomatosis, big and small lymphocytes and Hodgkin-cells, and in poorly differentiated lymphomas, the corresponding lymphoma cells are produced. The clinicist is at the beginning of drawing conclusions from prevalent kinetic disturbances.

SUMMARY After continuous 3 H-TdR infusion in vivo or incubation with 3 H-TdR in vitro human blood lymphocytes were examined by light-microscopic and electron-microscopic autoradio- graphy. Using relatively long autoradiographic exposure times (50-300 days) not only nuclear but also cytoplasmic labelling was visualized, the cytoplasmic label being present in up to 96 % of the cells. The cytoplasmic label was predominantly associated with the mitochondria and was removed from the cells nearly completely by treatment with DNase but not with RNase or cold perchloric acid. It is concluded that this cytoplasmic label mainly represents 3 H-TdR incorporated into mitochondrial DNA which is continuously renewed in an average turnover time of 14 days or less. This value is compatible with a turnover time of 11 days for mitochondrial DNA in mammalian cells reported in the literature.

The dilution in the circulating blood of lymphocytes lablled in vitro with 3H-cytidine was examined after autotransfusion in 9 patients with Hodgkin's disease (HD) stage II A-IV B, 5 of whom were untreated; in 2 untreated patients with carcinoma, and in 1 treated patient with scleroderma. The blood transit time of exchangeable lymphocytes was 37 +/- 18 min in the patients with HD and 26 +/- 6 min in the other patients. The proportion of exchangeable (recirculating) small blood lymphocytes was 39-84% in HD and 81-91% in the carcinoma patients. The relation between the size of the circulating pool of small blood lymphocytes and the total exchangeable (recirculating) lymphocyte pool was 1:20 to 1:30 in HD and 1:29 to 1:34 in the other patients. The absolute size of the recirculating pool of lymphocytes was 46-90 times 10(9) cells in HD and 100-150 times 10(9) cells in the carcinoma patients.

Autotransfusions of the DNA synthesizing blood cells from 2‐2.5 liters of blood, labelled in vitro with 3H‐thymidine, were performed in 2 patients with Hodgkin's disease. The fate of the labelled lymphoid cells was followed up for 5 min to 60 h in the circulating blood and occasionally in the lymph node tissue. The data indicate that 1) circulating DNA synthesizing large lymphoid cells leave the blood in less than 2 h; 2) they produce by mitosis large and medium sized lymphocytes, which mainly appear in blood and lymph nodes and 3) their generation time, in agreement with other estimates, is about 25 h.

At a time when chemotherapy of tumors with combined cytostatic agents is becoming a routine treatment and the range of effectiveness of such therapy is becoming evident as an increasingly large number of patients is treated, we can turn our attention to the body’s own immunological surveillance and possible ways of influencing it. With this in mind, it is evident that the problems resulting from drug-induced suppression of cellular and humoral immunity must be taken into consideration as well as the positive therapeutic effect (i.e. tumor regression or stoppage of tumor growth). However, there are as yet no standardized methods for determining the degree of immunosuppression in man and thus facilitating the determination of dosage of the cytostatic agents.