[Role of macrophages in graft rejection. I. New concepts on their role].
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Biomedical subjects
Publications and source records attributed to B Descamps.
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Detection of circulating and intra-articular soluble immune complexes, has been done in 28 rheumatoid arthritis, 8 mixed connective tissue diseases and 8 other connective tissue diseases. The method used, is based on a competition reaction in the antibody dependent lymphocytotoxicity reaction (ADC). In rheumatoid arthritis serum immune complexes were detected in 75% of the seropositive cases and 66% of the seronegative ones. The mean level of complexes is higher in the former form of the disease. In a given patient, the concentration of immune complexes in joint fluid, is higher than in serum. Immune complexes were present in the serum of 75% of patients with mixed connective tissue disease, but, here, at a concentration lower than in rheumatoid arthritis and systemic lupus erythematosus. It is proposed that measurement of serum immune complexes, can also be an interesting parameter in the follow-up of the patients.
Phagocytosis of altered red blood cells in vitro by mononuclear phagocytic cells is followed by profound depression of bystander lymphocytes' responses to antigen. Rapid endocytosis of transfused erythrocytes in vivo may transiently impair mononuclear phagocytic cell function, resulting in immunological unresponsiveness as observed in vitro. Transplantation at this time would be predicted to benefit from this attenuation of recipient immunocompetence, resulting in improved graft survival.
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Comparison between CDC and ADCC in a human allogeneic model using the same cytotoxicity marker, i.e. 51Cr release from labelled target cells, provided a better definition of the optimal technical conditions for revealing ADCC. Testing 229 sera from human renal allograft recipients after transplantation, we found that CDC is detected only during rejection (43% of cases) whereas ADCC can be found both in those recipients tolerating their grafts and in those undergoing rejection, more frequently in the former than in the latter (39% vs. 21%, p less than 0.05). These in vivo results and other in vitro experiments support the assumption that two distinct varieties of antibody can mediate the in vitro ADCC phenomenon, some directed against the A, B and C HLA loci and having a deleterious effect on the graft, and others capable of exerting a protective effect and which could be directed against D related HLA determinants.
The technique of heterotopic cardiac transplantation in the rat is described in detail. A simple, nontraumatic method of obtaining cellular prints from the heart is proposed for the study of cells infiltrating the allograft. Analysis of the morphological aspect of the cellular infiltrate present at the time of rejection in a series of allografts revealed a very high proportion of cells belonging to the monocyte-macrophage series, thus suggesting an important role for these cells in the rejection process.
Cytoenzymatic analysis of cells infiltrating heart transplants in the rat confirms the high participation of monocytes and macrophages. However, when comparing iso and allografts, only slight differences are observed in the lysosomal enzyme specific colorations, whereas a striking difference in these colorations is found between heart infiltrates and peritoneal exsudates from these recipients. This could favour the hypothesis of a local macrophage activating process within the graft but seems more probably due to differences in cell maturation stages.
Soluble immune complexes were detected using inhibition of antibody-dependent cell-mediated cytotoxicity (ADCC) in sera of patients with various diseases. Results were positive in 32/41 patients with rheumatoid arthritis (78%), in 27/38 systemic lupus erythematosus patients (71%), in 7/10 cutaneous lupus erythematosus patients (70%), in 6/8 mixed connective tissue disease patients (75%), in 11/26 membranous glomerulonephritis patients (42%), in 6/20 membranoproliferative glomerulonephritis patients (30%) and in 3/12 multiple sclerosis patients (25%). ADCC inhibition was compared with PEG precipitation technique and was found to be more sensitive for detecting soluble immune complexes. Various pitfalls are discussed.
Using the lymphocyte reaction (MLR) as an in vitro model of allogeneic response we have demonstrated that red blood cells (RBC), when phagocytosed by monocytes present in the reaction, induce almost complete suppression of the MLR. A similar effect is achieved by the RBC lysate or purified hemoglobin. These data strongly suggest that the better graft tolerance apparently induced by blood transfusion given to the recipient at the time of transplantation may result from a non specific immunodepressive process induced by the injected erythrocytes, and mediated by the monocyte.
This study, based on results of 252 cadaver kidney transplantations, shows that some factors which reflect individual immune response capacity, such as ability to produce anti-HLA antibodies, sex and response to hepatitis B virus, appear, along with HLA compatibility, to markedly influence renal graft survival and leads us to propose the following new guide-line for cadaver kidney recipient selection: For "good responders" (i.e., patients with anti-HLA antibodies, females and HBs Ag negative individuals) a close HLA compatibility with the donor (3 or 4 antigens in common) is necessary, while this need not be observed for "non-responders" (i.e., patients without preformed anti-HLA antibodies, males and HBs Ag persistent carriers). Furthermore, review of recent methods proposed for detecting early cellular and humoral manifestations of rejection leads to proposal of the following immunological monitoring of the transplant recipient. Systematic and frequent testing for circulating cytotoxic cells and antibodies against donor antigens, regular dosage of complement factors and of the nephretic factor, and investigations for the migration leukocyte inhibiting factor and macrophage arming factor, possibly produced in vitro by lymphocytes. Both these protocols for recipient selection and immunological monitoring can henceforth be applied and may contribute to improve cadaver kidney transplantation prognosis.
CBA Mice were immunized by two intraperitoneal injections of 30 X 10(6) DBA/2 or C57BL/6 spleen cells at days--12 and--2. Peritoneal cell population was obtained at day zero by washing the peritoneal cavity of Mice. Adherent cells were then separated using a 2 hrs. incubation in "Falcon" plates followed by washing. This macrophage-rich peritoneal cell population was found nonspecifically cytotoxic against 51Cr labeled tumoral target cells: P815 X DBA/2 mastocytoma cells, EL4 X C57BL/L lymphoma cells and spontaneous lymphoma AKR cells (same H--2k as CBA). This adherent peritoneal cell cytoxicity was demonstrated after 24 hrs. incubation with the target cells. It was found in nonspecific combination as well as when using target cells syngeneic to the donor. These findings suggest that adherent peritoneal cell cytotoxicity could be at least partly due to macrophages and result from factor (s) released by sensitized lymphocytes in vivo in the same way as has been previously demonstrated in vitro.
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HBs antigen (HBsAg) has been followed up every month in 440 hemodialyzed patients, typed for 26 HLA alleles of the A and B loci. An abnormally high rate of the HL-A-A1, B8 association (18.6%) was found in the group of patients able to eliminate HBsAg, when compared with the normal French population (5.05%, p less than 10(-4), and with the group of patients unable to eliminate HBsAg (7.0%, less than 0.01). Chronic aggressive hepatitis was only found in the latter. This high frequency of the HLA-A1, B8 association has also been found in patients with seronegative active chronic hepatitis and suggests that this phenotype might be associated with high immune response against HBsAg.
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Cell infiltration is commonly observed in human renal allograft biopsies. This infiltration was investigated using electron microscopy for a more precise assessment of the nature of these cells. More than 3000 cells infiltrating twenty-five renal allograft biopsies were studied. Six cellular types were distinguished and a mean percentage of each type was calculated. Only one-half of these cells were normal or transformed lymphocytes (including small lymphocytes: 22-3 +/- 3-8%, 'intermediary' cells: 22 +/- 3-6%, blast-like cells similar to MLC transformed lymphocytes: 8-1 +/- 2-4%. A relatively high number of plasmocytes (12-4 +/- 2-5%) and a still higher percentage of macrophages (28-5 +/- 4-6%) were found. Granulocytes represented only 2 +/- 0-8%of the cell population. Variations of the mean percentage of these cellular types were studied in various clinical situations.