Hematopoietic stem cells in the hereditarily anemic Belgrade laboratory (b/b) rat.

The Belgrade (b/b) rat has hereditary hypochromic microcytic anemia as the consequence of intracellular iron deficiency. Studies in the b/b rat have also demonstrated alteration in hematopoiesis at the progenitor cell level. In the present study, investigations were extended to the bone marrow hematopoietic stem cells as determined by measurements of marrow repopulating ability (MRA) and day 8 spleen colony-forming units (CFU-S-8). A reduced number of CFU-S-8 per femur was found, together with a low incidence per 10(5) bone marrow cells and a nondetectable proliferation rate. The proliferation rate did not increase after treating b/b rat bone marrow cells in vitro with a stimulator for CFU-S proliferation, indicating a proliferative block. The treatment of b/b rats with iron enhanced the proliferation rate and partially increased the number of CFU-S-8 in bone marrow. Chronic transfusion of b/b rats with washed RBC from non-anemic animals restored both the number and the proliferative response of bone marrow CFU-S-8. The MRA of b/b rats was reduced, but in proportion to the decrease in the bone marrow cellularity of these animals. MRA (pre-CFU-S) of b/b rats recovered completely after both iron treatment and chronic transfusions, suggesting that changes in the pre-CFU-S pool are secondary rather than directly induced by the genetic defect. These results indicate the importance for stem cell proliferation of normal oxygenation--the arterial oxygen content in b/b rats is six times lower than in (+/+, b/+) rats--which recovered after the iron treatment and was completely restored after chronic transfusions. High-dose iron therapy abrogated the proliferative block of CFU-S-8, but number of CFU-S-8 was not completely recovered in spite of normalized oxygenation, indicating a possible suppressive effect of iron overload on the marrow microenvironment.

Continuous versus split-course irradiation for lung cancer. Immunological implications.

The therapeutical irradiation for lung cancer causes profound disturbances of host's general immunocompetence, the cellular immunodepression being the dominant finding. It is thought that split-course technique holds certain advantage over the continuous irradiation, since the former includes an interruption of 4 week duration, thus allowing the lymphopoietic system to recover to a certain degree. In this report, we compared the radiotherapy-due alterations of several parameters of cellular immunity (the number and function of total T cells, active T cells and the cells of monocyte/macrophage lineage), immediately after the completion of therapy in either continuously (n = 13) or split-course-irradiated (n = 12) lung cancer patients. All patients had received the total dose of 60 Gy. Both therapeutical techniques caused alterations of the parameters tested: the significant decrease of the total and active T cells and their proliferative responses, while the phagocytic activity and the number of mononuclear phagocytes were increased, the latter being affected to a lesser extent in split-course-treated patients. Our results suggest that both techniques have similar immunodepressant effect on the cellular immunity of lung cancer patients.

Immunomodulation in vitro. The predictive value of in vitro testing of lung cancer patients' lymphocyte responsiveness to stimulation by Thymex L. A preliminary report.

Eleven lung cancer patients were selected for combined radio and immunotherapy with a thymic agent-Thymex L. The selection criteria included the pre-therapy testing of patients' immunocompetence and the responsiveness of their lymphocytes to the in vitro addition of Thymex L: only patients with a significant degree of immunodepression, whose depressed cellular immunity parameters (the number of total and active T cells and their mitogen-induced lymphoproliferative response) were significantly increased upon this agent's action in vitro, entered the study. The results of the pre-therapy in vitro stimulation correlated with those obtained after completion of radioimmunotherapy: the administration of Thymex L along with radiotherapy seances prevented iatrogenic deterioration of initial depression of general immunocompetence and enabled to overcome it to a certain degree. This indicates that pre-therapy in vitro testing has a true predictive value. However, the initial immune disturbances were not normalized by immunotherapy; the post-therapy testing of the patients' lymphocytes to the addition of Thymex L in vitro showed that these cells possessed a residual potential to respond by a significant increase of the active T cell number and proliferative capacity, suggesting that immunotherapy could be prolonged in order to potentiate cellular immunity in immunodepressed lung cancer patients.

[In vitro reactivity of lymphocytes after the addition of immunostimulatory drugs]. / Reaktivnosti limfocita in vitro na dodavanje imunostimulacionih sredstava.

The in vitro immunomodulating, effects of two thymic extracts--Thymex L and Thymomodulin--on lymphocytes of lung cancer patients, were studied. The number of total and active T cell and PHA-induced lymphoproliferative response were evaluated before and after the addition of two different concentrations (5 mg/ml and 0.5 mg/ml) of these agents. The in vitro incubation with Thymex L and Thymomodulin had no effect on the number of total T lymphocytes, but the active T cells and proliferative responses were significantly higher. This increases was observed in the majority of patients with diminished baseline values. These results indicated that several immunological parameters should be used in vitro testing of an immunomodulatory drug. They also indicated the need for in vitro testing selection of candidates for immunotherapy among immunodepressed cancer patients.