[en] Indium-111 oxine is currently used to label peripheral lymphocytes in order to study the kinetics of these cells in vivo. Since the quantity of radioisotope for labelling is still a matter of controversy, the authors have investigated in vitro the effect of increasing the concentration of indium-111 oxine on the lymphocyte surface phenotype and the antibody-dependent cellular cytotoxicity (ADCC) using lymphocytes from normal subjects. The cell surface phenotype, as evaluated by 2 monoclonal antibodies, was not affected whereas ADCC, at any of the doses used, was significantly reduced compared to the baseline value. The implications of these results for the use of indium-111 oxine for the in vivo studies are discussed. (Auth.)

[en] When plating equal samples from different syngeneic mice, variations appearing in plaque-forming cell (PFC) numbers largely exceed the methodological variations obtained after the replicate plating of cells from a single animal. Theoretically, these non-genetic variations of the immune response can result from individual differences either in the composition of the immunocompetent cell population or in the microenvironmental factors (hormonal and others) influencing the cells. In irradiated recipients restored by the transfer of syngeneic spleen cells, the PFC variations may be considered as the cumulative effects of the cellular status of the donor and of the microenvironmental factors of the recipient. In attempting to estimate the relative importance of these variations, the authors studied the response of spleen cells after different transfer proceedings. (Auth.)

[en] Allogeneic, H-2-incompatible irradiation chimeras (H-2sup(d) → H-2sup(b)) constructed with normal, unmanipulated bone marrow and with marrow-derived factors live long and do not manifest a GvH disease. Their response to primary immunization is deficient but their alloreactivity is normal. This chimeric allotolerance cannot be passively transferred from chimeric donors to normal irradiated recipients. Passive transfer of both donor- or recipient-type immuno-competent T-cells into the chimeric mice does not lead to syngeneic reconstitution, rejection of the engrafted marrow or GvH disease, and the mice maintain permanently their chimerism. This new model demonstrates that chimerism is not eradicable in long-lived chimeras reconstituted with unmanipulated bone marrow, and that the bone marrow itself plays a dominant role in maintenance of chimerism. (Auth.)

[en] A simple method for rapid determination of IgG-containing circulating immune complexes by commercially available reagents was developed. In this method, serum is incubated with 2.5% polyethyleneglycol. After washing, the precipitate is incubated with radioactively labeled protein A, which binds to IgG in the immune complex. After a further washing, the radioactivity bound is measured. Artificially formed complexes of heat-aggregated human IgG are diluted and a reference curve is constructed. This method is compared to the solid phase Csub(1q) binding method. (Auth.)

[en] The effect of X-ray irradiation on IgG membrane receptors of B murine lymphocytes was studied. Cells were obtained from peripheral lymph nodes of RK mice and teased in Hank's solution. The cells were irradiated or kept as control samples, incubated at 37⁰C, with or without drugs with known biochemical action at metabolic or structural levels, and labelled with fluorescein-conjugated anti-IgG antisera. The results show that X-ray irradiation results in a modulation of IgG receptor molecules on B-cells. The disappearance phase which takes only 10 min, is temperature dependent, and is prevented with metabolic inhibitors, microtubular disruptors, db-cAMP and local anesthetics. The re-appearance phase is also temperature dependent but apparently does not have either energy or cytoskeleton participation. The phenomenon is interpreted as partial and transient internalization of IgG molecules in the membrane. (Auth.)

[en] Recently it was shown that the induction of antibodies against the H-2 antigens after multiple platelet transfusions is due to leukocyte contamination of the platelet suspensions. Pure platelets are not able to induce a primary antibody response. The present study shows that the platelets, however, can be recognized by the immune system but they induce a suppression of the response. Mice pretreated with donor platelets will not give a primary antibody response upon a subsequent injection of donor leukocytes and the survival of donor skin grafts will be prolonged. Similar results were obtained by pretreatment of the responder mice with heat-treated donor leukocytes. Furthermore, repeated injections of heat-treated leukocytes of the recipient strain to the donor before bone marrow grafting, will graft-versus-host mortality. The recipient mice were irradiated and received spleen cell injections. These data show that cells which have only class I antigens on their surface and no activating class II antigens, induce a suppression of the response against class I antigens. (Auth.)

[en] The intervention of adrenaline in the immunoregulation was investigated through the modification of the anti-SRBC PFC response of mice after its i.p. administration (4 μg) at various intervals before SRBC antigen. When the interval was less than 24 h, adrenaline accelerated the immune kinetics. This modification was apparent on both direct and indirect PFC, as well as on naive and immune mice. However, mice treated from 2 days showed a suppression of the response. The adrenaline affect subsisted on the adoptive response of spleen cells drug-treated either in vivo or in vitro. The mitogenic response after in vitro PHA or LPS stimulation of spleen cells from adrenaline-treated mice indicated that the T-cells were the drug target. The physiological role of the adrenaline and immunological influences of acute stress are discussed in the paper. The stress was provided by gamma irradiation. (Auth.)

[en] A survey of the appearance of natural antibodies in C57BL/6 mice, measured by a complement-dependent cytotoxicity test against syngeneic radiation leukemia virus-induced lymphoma, was performed. Activity could be detected in sera from 5- to 14 month-old animals. This activity could be attributed mainly to IgM antibodies until the age of 10 months, whereas an increasing level of IgG-like antibodies was demonstrated in sera from 12-month-old mice. (Auth.)

[en] Experiments were carried out to specify the adrenaline target among the immunocompetent cells. Adrenaline administered for some hours exerted opposite effects on the natural PFC and RFC: the first were enhanced and the second significantly reduced. These paradoxical results were interpreted as a consequence of the inhibition of the suppressor T-cells in the resting status. Adrenaline appeared to act on the sensitive cells through beta- rather than through alpha-receptors. Further experiments on the adrenaline influence on the syngeneic barrier phenomenon and on the cellular balance at its termination seemed to indicate that adrenaline was directly inhibitory for the Ts but not for their precursors. These results are discussed in the light of the cellular networks regulating the immune response. Irradiated mice were compared with non-irradiated mice as described in the previous article. (Auth.)

[en] Mice were immunosuppressed by means of whole-body irradiation or cyclophosphamide, in order to investigate the influence on the initial phase of infection induced by a strain of the fungus, Paracoccidioides brasiliensis, in the yeast phase and inoculated intraperitoneally. A group of mice was irradiated with 600 rad (cobalt γ-irradiation) 24 h before infection. Two groups were treated with cyclophosphamide (200 mg/kg intravenously), one two days before, and the other, one day after infection. A control group received the fungus, but no radiation of cyclophosphamide. All animals developed lesions at the site of inoculation. Metastatic lesions were observed in 100% of the animals in the irradiated group, 67% in each of the cyclophosphamide-treated groups and 33% in the control group. These lesions were found both in the liver and lungs, being more numerous in the irradiated group, followed by the cyclophosphamide-treated group in which the drug was given after the infection; they were slight in both viscera in the other cyclophosphamide-treated group and also slight in the liver and absent in the lungs of the controls. (Auth.)