Annales d'immunologie最新文献

Immune complexes from patients with subacute endocarditis were used to develop a methodology for characterization of the antigen involved in human circulating immune complexes. This model was chosen because it permits isolation of the causative agent of the streptococcal infection thought to contain the antigen present in the immune complex. A comparison was made between two methods for characterization of bacterial antigen bound to antibody. In the first, animals were immunized with purified immune complexes and the production of antistreptococcal antibodies was investigated. In the second method, a sandwich ELISA was developed, implying the double specificity of the immune complex (human immunoglobulin and streptococcal antigen). The latter method gave the best results, detecting antigen in the immune complexes of 8 out of 10 patients' sera. The application of this method to other immunopathological situations is discussed.

C3 was bound to human erythrocytes from autologous plasma or from serum brought to low ionic strength (mu less than or equal to 0.03) and pH between 4.0 and 5.0, then subsequently incubated with erythrocytes (50/1, v/v) for 20 min at 0 degree C. This capacity was preserved up to 72 h by prolonged incubation at 20, 25 or 37 degrees C, whereas it was quickly lost by incubation at 0 degree C. C3 binding did not require complement activation and was not observed with neuraminidase-treated erythrocytes. Crossed immunoelectrophoretic analysis of the pretreated serum or plasma revealed that a fraction having more cathodal migration than that of native C3 was generated upon incubation in the above-mentioned conditions. This fraction appeared able to selectively bind to the erythrocytes. Cell-bound C3 reacted positively to antisera against C3a, C3c, C3d or native C3; they rosetted positively with EAC3b, clearly showing that this C3 binding was not dependent on the proteolysis of C3 and that it concerned the acceptor sites on the cells, since C3b receptors were free. The functional significance of this C3 binding was also investigated: EC3 were not able to lyse through the alternative pathway, whereas lysis clearly increased when C3 was found to AET-treated erythrocytes. This finding, together with the modulation in the capacity of EC3 or E(AET)C3 to form an alternative pathway convertase by antibodies to C3c or C3d, strongly suggests a contribution of bound C3 to such a convertase. In contrast to "C3b-like" C3, this modified C3 was able to bind to acceptor sites on erythrocytes but, like the former, it retained the capacity to form an alternative pathway convertase. In this light, it may represent an intermediate between C3 and "C3b-like" C3.

Inflammation was induced in the dorsal area of pathogen-free mice following subcutaneous injection of polyacrylamide microbeads (Biogel) of varying particle size (200-400 mesh) and pore size (exclusion limit ranging from a molecular weight of 2,000 to 300,000). Six days after injection of the microbeads, mice were infected with 10(5) Listeria monocytogenes. Only animals injected with "Biogel P2, P4, P6" (exclusion limit 2,000, 4,000 and 6,000 respectively) survived this lethal inoculum of Listeria. A study of the kinetics of this increased resistance revealed that homogenates of granulomas, induced eight days before injection into mice, significantly decreased the number of listeria in the spleen of treated mice. Such increased resistance was not found in cell homogenates, but only in the exudate of 8-day old granulomas. Fractionation studies of the inflammatory exudates with ammonium sulfate showed that immunostimulating substance were present in the supernatant following precipitation with 80% saturated (NH4)2SO4.

Spleen cells from C3H/HeN mice treated with BCG or Mycobacterium smegmatis displayed similar increased antibody-dependent cellular cytotoxicity (ADCC) in vitro. This activity, which increased between the tenth and the thirty-first day after stimulation, reached twice the amount of ADCC activity developed by the control spleen cells. C3H/HeN mice treated with a complete adjuvant including M. smegmatis and squalene displayed a lower increase in their ADCC capacity (30% instead of 100%).

Two monoclonal antibodies recognizing monomorphic determinants on class I antigens of MHC were characterized. They were shown to recognize beta 2m by cytotoxicity inhibition studies. The epitopes recognized were different, as assayed by cross-inhibition and phylogenetical studies. One antibody recognized free as well as HLA-associated beta 2m. The other reacted with a conformational epitope which was well conserved during evolution.

Immunoelectrophoresis is the usual method for identifying abnormal bands detected by zone electrophoresis. In the last few years, a new technique has appeared, that of immunofixation. This method involves an antibody-antigen precipitation reaction in an electrophoretic strip. The aim of the present study was to compare immunofixation (IFX) and immunoelectrophoresis (IEP) of 101 sera with one or more homogeneous bands upon serum protein electrophoresis: among them 97 bands were subsequently characterized by IFX on agarose gel, and only 50 by IEP. IF appears to be a more sensitive technique for characterizing M-components, especially those with multiple bands. While more rapid than IEP, this new procedure does not seem appropriate for routine use.

Purified alpha 1-antitrypsin (alpha 1AT) was previously shown to prevent primary antibody response and lymphocyte DNA synthesis. We have reported that radiolabelled alpha 1-AT could bind to human lymphocytes and inhibit surface proteolytic activity. However, the radiolabelling method brings no information on the eventual heterogeneity of alpha 1AT distribution among the population nor on the presence of alpha 1AT on untreated lymphocytes. In this report, we have investigated these two points using indirect fluorescence followed by flow cytofluorometric analysis. The presence of alpha 1AT was revealed on a variable percentage of untreated peripheral blood and tonsillar lymphocytes. The incubation of cells with additional alpha 1AT induced an increase of the percentages of fluorescent lymphocytes. This binding was specific and could be inhibited by pretreatment with the protease inhibitor tosyl-L-phenylalanine-chloromethyl-ketone (TPCK) (2 X 10(-5)M). Furthermore, TPCK and EDTA (3 mM) could displace alpha 1AT initially bound to the lymphocyte surface.

Swiss mice were immunized with various antigens: polyvinylpyrrolidone (PVP), human serum transferrin (HST), bovine serum albumin (BSA) or tetanus toxoid (TT). Fifteen days after the last injection of antigen, the mice were infected with Plasmodium chabaudi AJ. Two weeks after the beginning of malarial infection, parasitaemia became latent and total gammaglobulin levels, as well as IgG and IgM levels, were significantly increased. At that period the antigen-binding capacity (ABC) and the total antigen-binding Sites (Abt) were determined for PVP, HST and BSA. It appeared that the ABC and Abt of anti-HST or anti-BSA antibodies were lower than those of corresponding uninfected controls. With regard to anti-PVP antibodies, only the Abt was modified after infection, but not the ABC. The evolution of anti-TT Ab levels determined by a solid-phase assay with 125I-TT was as above with a marked decrease on and after the 4th week of infection. Injection of low-density lipoproteins (LDL) from day-9-infected mice to TT-immunized mice significantly reduced anti-TT antibody levels. At similar doses, LDL from normal mice did not induce an inhibitory effect. At mouse-equivalent-dose, LDL from infected mice revealed an inhibitory effect compared to LDL from uninfected controls. Our results suggest that LDL from P. chabaudi-infected mice can exert an immunoregulatory role and thus could explain part of the immune impairment observed during the infective process. Moreover, from the present data it might be postulated that the hypergammaglobulinaemia of P. chabaudi infection does not result from a parasite-potentiating effect on a pre-existing antibody response.

The levels of immunoglobulins in the seminal plasma of healthy males were compared with those of oligospermic patients. The results show markedly increased levels of IgG in oligospermic patients. The presence of IgM, which has not been detected in the seminal plasma of healthy males, was estimated in some of the oligospermic patients. The authors recommend this simple screening test to be carried out in every male infertility follow up.