[en] The proliferative response to mitogenic stimulation by splenocytes can be augmented by exposing mice to whole-body, chronic, intermittent low doses of ionizing radiation, referred to here as low-dose irradiation. The purpose of this study was to identify the cell(s) in the spleen which is responsive to the proliferation-augmenting effect of low-dose irradiation, i.e., the cellular target. C57BL/6 mice were subjected to low-dose irradiation or to sham irradiation. Three days after the last exposure, spleens were removed, separated into cell fractions which were nonadherent and adherent to plastic surfaces and reconstituted in various combinations, and their proliferative responses to various mitogens were determined. Highly purified T cells were also used in place of the nonadherent cell fraction in the reconstitution studies. THe target cells were shown to be T cells. The target T cells of low-dose-irradiated mice possessed elevated constitutive levels of HSP070 mRNA and HSP-72, and they responded to T-cell receptor-specific anti-CD3 stimulation by producing more HSP-70 mRNA and HSP-72 and by proliferating more extensively than T cells of sham-irradiated mice. 30 refs., 3 figs., 1 tab

No abstract available

[en] The effect of exposure to tritiated water on Plaque-forming cell (PFC) in spleen of BALB/c mice were studied with the liquid-phase monolayer plaque-forming cell technique. After 3 days exposure with i.p. injected tritiated water at a constant dose rate, the PFCs were inhabited exponentially at a dose range from 0.047 to 1.270 Gy. When the dose reached 1.270 Gy, approximately 99% of the PFCs were killed. There was a similar effect of exposure to the tritiated water on the spleen weight and spleen cell number

No abstract available

[en] The kinetics of post-irradiation haemopoietic tissue recovery was studied by evaluating quantitatively the results from histologic studies of the kinetics of endogenous erythroid spleen colony counts in subserial sections of spleens from mice irradiated with 5, 7 or 9 Gy of ⁶⁰Co γ-rays at intervals of 4, 6, 8, and 10 days following irradiation. Emphasis was put on the individual types of colony-forming cells and on time intervals at which these cells enter into action. Large numbers of rapidly maturing microscopic erythroid colonies appeared between 8 and 10 days after irradiation. From this finding we conclude that in addition to colony-forming cells giving rise to macroscopic colonies, large numbers of already differentiated progenitor cells - the products of the first regeneration wave with a peak approximately 6 days following irradiation -participate in the second wave of regeneration which is typically manifested from day 10 after irradiation. (author). 4 tabs., 23 refs

[en] The mechanism of splenic incorporation of ⁶⁷Ga in chronic myelocytic leukemia (CML) was evaluated. Nine cases (82%) out of 11 chronic cases of CML, ⁶⁷Ga was incorporated more heavily in spleen more than in bone marrow or in liver. These findings correlated with splenic extramedullary erythropoiesis on ferrokinetic measurements. No splenic images were obtained in 5(62.5%) out of 8 cases with blastic crisis, and in 3 cases (37.5%), splenic uptake was demonstrated, of which uptake was lower than hepatic or bone marrow accumulation. Cellular uptake of ⁶⁷Ga into mononuclear and polymorphonuclear cell fraction in patients with CML was investigated by Ficoll-Hypaque gradient separation. Forty-eight hours after the injection, mononuclear cell fraction which contained CML immature cells had 10.3 times higher radioactivity than polymorphonuclear fraction. Splenic higher radioactivity in chronic phase of CML which mainly depended upon the CML immature cells might suggest splenic extramedullary hematopoiesis. ⁶⁷Ga scintiscan would be useful to detect the splenic extramedullary hematopoiesis without performing splenic biopsy nor ferrokinetic body surface counting measurements. (author)

[en] A case report is presented of a 60 year old man whose prolympocytic leukemia responded to lymphocytapheresis (one procedure) and Splenic irradiation (1 Gy 3 times a week, total dose 10 Gy.) A fast and stable clinical and analytic response was obtained during 12 months. (UK)

No abstract available

[en] Spleen cells from untreated young male and female C57BL/6 and C58 mice and of male C3H/He mice showed cytotoxic activity in vitro against BALB/c x-radiation-induced leukemia RL male 1 cells by ⁵¹Cr-releasing lymphocyte-mediated cytotoxicity (LMC) tests, but old mice of these strains lacked LMC activity. In contrast, spleen cells from male and female AKR, BALB/c, and DBA/2 mice, and from female C3H/He mice had no appreciable LMC activity. The proportion of active cells in spleens from young (C57BL/6 x BALB/c)F₁ or reciprocal hybrid mice was higher in females than in males. The specificity of the LMC reaction of RL male 1 cells, determined by LMC inhibition assays, was somewhat different from that of previously reported serologic X.1 tests. Thus the antigen detected by LMC has been tentatively designated X.1'. The main effector cells in this system were uncharacterized cells not adherent to glass surfaces or nylon--wool columns. These findings in RL male 1 leukemia extend the evidence for the presence of naturally occurring LMC. With the single unexplained exception of strain C3H/He, the LMC activity against RL male 1 cells, exhibited by untreated mice of various strains, corresponded with a previous classification of mouse strains immunologically as X.1 responders or as X.1 nonresponders according to their ability to reject X.1-positive leukemia cells. (auth)

[en] Arsenic is known to produce inhibition as well as induction of immune cells proliferative responses depending on the doses as one of its mechanisms of immunotoxicity. Here we evaluate the effect of arsenic exposure on the activation of splenic mononuclear cells (SMC) in male CD57BL6N mice. Intra-gastric exposure to arsenic (as sodium arsenite) for 30 days (1, 0.1, or 0.01 mg/kg/day), reduced the proportion of CD4+ cells and the CD4+/CD8+ ratio in the spleen, increasing the proportion of CD11b+ cells. Arsenic exposure did not modify the proportion of B cells. SMC showed an increased level of phosphorylation of lck and fyn kinases (first kinases associated to TCR complex when activated). Although normal levels of apoptosis were observed on freshly isolated SMC, an increase in apoptotic cells related with the increase in phosphorylation of lck and fyn was observed when SMC were activated with Concanavalin-A (Con-A). Arsenic exposure reduced the proliferative response of SMC to Con-A, and also reduced secretion of IL-2, IL-6, IL-12 and IFNγ. No effect was observed on IL-4, and IL-10 secretion. The same effects were observed when SMC of exposed animals were activated with anti-CD3/CD28 antibodies for 24 h, but these effects were transitory since a recovery, up to control levels or even higher, were observed after 72 h of stimulation. This study demonstrates that repeated and prolonged exposure to arsenic alters cell populations and produces functional changes depending on the specific activation pathway, and could be related with the phosphorylation status of lck and fyn kinases