The immune system in isolated IgA deficiency

The immune systems were compared in 23 subjects with isolated IgA deficiency and 15 controls with normal levels of IgA. The IgA deficient group had higher levels of serum IgM, and lower stimulation indices for the mitogens Con A, PWM and PHA; only the index for PHA was statistically significant. Their suppressor T-cell activity was decreased and chemotactic activity significantly decreased. They also exhibited a decrease in Leu 3, and a significantly lower ratio of Leu 3 to Leu 2. The mean percent of positive NBT neutrophils was decreased. An imbalance in the immunoregulatory mechanism is suggested as a possible explanation for IgA deficiency.     

Effect of aminonucleoside nephrosis on immune complex localization in autologous immune complex nephropathy in rats.

The effect of increased capillary permeability on glomerular immune complex localization was studied in rats immunized with proximal tubular antigen (Fx1A) to induce autologous immune complex nephropathy (AICN). AICN rats were made proteinuric by injection or unilateral renal perfusion with aminonucleoside of puromycin (PA) before developing subepithelial complex deposits. Control AICN kidneys developed diffuse granular deposits of IgG and Fx1A on the subepithelial surface of the glomerular basement membrane (GBM) at 3 wk by immunofluorescence and electron microscopy, and deposits increased in subsequent weekly biopsies. In contrast, PA-nephrotic AICN kidneys developed few or no GBM deposits and a significant increase in mesangial localization of IgG and Fx1A during the period of PA-induced proteinuria. These alterations in complex localization were documented both in rats with PA nephrosis and in unilaterally PA-nephrotic kidneys compared with contralateral controls in the same animals, thus excluding any effect of PA on the immunopathogenetic mechanism in AICN as an explanation for these findings. The absence of GBM deposits closely correlated with reduced staining for polyanionic glomerular sialoprotein in proteinuric kidneys, since PA-perfused kidneys studied 2 wk after resolution of proteinuria demonstrated return of normal staining for sialoprotein and development of subepithelial complex deposits similar to those in contralateral control kidneys. These studies demonstrate that properties of the glomerulus itself play an important role in determining the site of complex deposition in experimental AICN and suggest that electrophysical characteristics of the glomerular capillary wall may influence complex localization on the GBM.     

Treatment of autologous immune complex glomerulonephritis with vasoactive amine antagonists.

AIC nephritis produced in rats by a single injection of FxIA in CFA was treated by agents with known antihistamine and antiserotonin activity. The effect of this drug regimen in altering the deposition of Ag-Ab complexes in the glomerulus was assessed by light, immunofluorescent, and electron microscopy. The vasoactive amine antagonists Chlortrimeton, Vistaril, Azatadine, and Sansert, when given singly or in combinations which completely abrogated histamine and serotonin-induced skin wheal formation, were unsuccessful at reducing apparent glomerular deposition of the circulating immune complexes of AIC nephritis.     

Single and multiple drug therapy in autologous immune complex nephritis in rats.

Autologous immune complex (AIC) nephritis is a form of chronic renal disease with remarkable similarities to idiopathic membranous nephropathy occurring in man. AIC nephritis was induced in 160 gram Lewis rats with a single footpad injection of tubular brush-border antigen (FxIA) in complete Freund's adjuvant. When killed at 8 weeks, 85 per cent of the rats demonstrated typical diffuse glomerular deposits of immunoglobulin G and B1C (C1/3 component of complement) by immunofluorescent microscopy, and subepithelial electron-dense deposits by electron microscopy. Both immune complex disease and significant proteinuria occurred in two-thirds of these animals. An attempt to modify the natural course of established AIC nephritis using large doses of potent glucocorticoids (methyl-prednisolone), anti-inflammatory agents (acetylsalicylic acid, indomethacin, and cyproheptadine), and immunosuppressive drugs (cyclophosphamide, azathioprine) was begun 4 weeks after initial immunization and continued for 4 more weeks. None of the single drug nor multiple drug protocols employed was of demonstrable benefit in ameliorating the immune events operating in AIC nephritis. Cyclophosphamide and indomethacin, when used singly, were associated with significant mortality in the animals studied. All combined drug protocols involving glucocorticoids and antimetabolites were associated with unacceptable mortality as well. Of interest, immune complexes could not be demonstrated in the vascular choroid plexus of any rat with AIC nephritis. This failure to modify the course of established renal disease (AIC) in an experimental animal with generally available pharmacologic agents, is similar to the usual results of such treatment in chronic renal disease (idiopathic membranous nephropathy) in man. It is possible that new and more potent anti-inflammatory agents employed singly or in various combinations, will permit more successful manipulation of the host's immunologic system to prevent or modify immune injury of the renal glomerulus.     

The influence of selective thrombocytopenia on immune complex glomerulonephritis.

Anticoagulation in experimental GN has not uniformly reduced inflammation and prevented functional impairment. The observation that platelet thrombi are occasionally present in nephritic kidneys prompted the suggestions that platelet aggregation may play a fundamental role and that inhibition of aggregation may be of therapeutic value. To test this hypothesis, the effect of selective platelet depletion on acute IC GN in the rabbit was evaluated. IC GN was induced with bovine albumin, and platelet depletion with APS. Platelet depletion preceded proteinuria by more than 36 hr and was sustained for 5 days. Platelet accumulation within the nephritic kidney was quantitated with chromium-labeled platelets. The hemodynamic effect of parenteral administration of APS on the evolution of IC GN was assessed by comparing IV with IP administration. Thrombocytopenia in the absence of hypotension had no inhibitory effect on IC GN, nor was there platelet accumulation within the nephritic kidneys of the platelet-depleted animals. These results indicate that platelet aggregation is not essential in the pathogenesis of IC GN and that inhibition of platelet aggregation may be of little value.     

Naturally occurring IgM antibodies to a small RNA insect virus in some mammalian sera in New Zealand

Antibodies to cricket paralysis virus were demonstrated in sera from a pig, a horse, and numerous cattle in New Zealand. The reactions in immunodiffusion tests were variable, but significant and consistent reactions were obtained with these sere in virus neutralization assays using Drosophila cells. The sedimentation coefficient of the antibodies was 19S, and their activity was destroyed by treatment with 0.1 M 2-mercaptoethanol, indicating that they were of the IgM class.     

Circulating immune complexes in IgA nephropathy consist of IgA1 with galactose-deficient hinge region and antiglycan antibodies

Circulating immune complexes (CICs) isolated from sera of patients with IgA nephropathy (IgAN) consist of undergalactosylated, mostly polymeric, and J chain-containing IgA1 and IgG antibodies specific for N-acetylgalactosamine (GalNAc) residues in O-linked glycans of the hinge region of IgA1 heavy chains. Antibodies with such specificity occur in sera of IgAN patients, and in smaller quantities in patients with non-IgA proliferative glomerulonephritis and in healthy controls; they are present mainly in the IgG (predominantly IgG2 subclass), and less frequently in the IgA1 isotype. Their specificity for GalNAc was determined by reactivity with IgA1 myeloma proteins with enzymatically removed N-acetylneuraminic acid (NeuNAc) and galactose (Gal); removal of the O-linked glycans of IgA1 resulted in significantly decreased reactivity. Furthermore, IgA2 proteins that lack the hinge region with O-linked glycans but are otherwise structurally similar to IgA1 did not react with IgG or IgA1 antibodies. The re-formation of isolated and acid-dissociated CICs was inhibited more effectively by IgA1 lacking NeuNAc and Gal than by intact IgA1. Immobilized GalNAc and asialo-ovine submaxillary mucin (rich in O-linked glycans) were also effective inhibitors. Our results suggest that the deficiency of Gal in the hinge region of IgA1 molecules results in the generation of antigenic determinants containing GalNAc residues that are recognized by naturally occurring IgG and IgA1 antibodies.     

Autoantibodies, including antibasement membrane antibody, in patients with selective IgA deficiency

Laboratory data are presented on 48 patients with selective IgA deficiency. Sixty percent of the patients had autoimmune diseases or related disorders. We found antibasement membrane antibody (ABMA) in the sera of four IgA deficient patients and the incidence of ABMA seemed to be related to clinical symptoms. The incidence of various other antibodies was found to be increased in selective IgA deficiency. This phenomenon might be derived from the lack of local immune system. Inadequate IgA barrier might permit the exessive gastrointestinal absorption of food antigens or autoimmunogens in metabolic products which are excreted into the gut lumen.     

The significance of the presence of anti-IgA antibodies in individuals with an IgA deficiency

Abstract. Class specific anti-IgA (anti-α) antibodies were found in seven out of sixteen patients in whom serum IgA was not demonstrable by the Mancini method (sensitivity down to 0.02 mg/ml). Allotype specific anti-IgA [anti-A₂m(l)] antibodies were found in an eighth patient. The anti-IgA antibodies proved to be of the IgG class. In the eight patients with anti-IgA antibodies, the presence of these antibodies could not be ascribed to immunization by administration of blood products. Isoimmunization in pregnancy and absorption of colostral IgA or animal IgA were other possible causes of anti-IgA antibodies.–Using a combined IgA/anti-IgA radioimmunoassay very low IgA levels (0.00013-0.020 mg/ml) were demonstrable in patients without anti-IgA antibodies whose serum IgA levels could not be determined by the Mancini method.–IgA metabolism was studied in five IgA-deficient patients. In two patients the rate of degradation of ¹³²I-IgA almost equalled that in individuals with a normal serum IgA level. In three patients, however, the rate of degradation was greatly increased. In their sera, in contrast to the first two, class specific anti-a antibodies were demonstrated.–One of these patients showed an anaphylactic reaction immediately after intravenous injection of ^mI-IgA. Only this patient showed complement fixation by the IgA/anti-IgA complex and IgA stimulation of lymphocytes.–The presence of anti-IgA antibodies has some important practical implications for those patients who need blood products.     

Histocompatibility antigens and genetic control of the immune response in guinea pigs. III. Specific inhibition of antigen-induced lymphocyte proliferation by strain-specific anti-idiotypic antibodies

The in vitro T-cell proliferation induced by penicilloylated bovine IgG (BPO-BGG) in sensitized strain 2 and strain 13 guinea pigs could be specifically blocked by strain-specific antisera presumably directed against cell membrane-associated immunoglobulin idiotypes. The anti-idiotypic antisera were prepared in strain 2 and strain 13 guinea pigs against immunoadsorbent purified anti-BPO-BGG antibodies which had been raised in strain 2 and strain 13 animals. Strain 13 antistrain 13 anti-BPO-BGG (a strain 13 BPO-BGG) suppressed the in vitro BPO-BGG response of cells from immunized strain 13 animals but did not inhibit the response of cells from immune strain 2 animals. Conversely, the corresponding antiserum raised in a strain 2 combination (a strain 2 BPO-BGG) only inhibited the in vitro BPO-BGG response of strain 2 cells. Furthermore, the inhibitory activity of the antisera could only be absorbed by immune cells from the syngeneic strain. The activity of the a strain 13 BPO-BGG serum was highly specific; the inhibitory activity could only be absorbed by BPO-BGG-sensitive strain 13 cells. The inhibitory activity of the anti-idiotypic sera was predominantly associated with the 19S fraction. The data suggest that immune cells and in particular T lymphocytes from strain 2 and strain 13 guinea pigs possess strain-specific recognition structures from BPO-BGG with the same idiotypes as the corresponding strain-specific immunoglobulins. Furthermore, the production of such inhibitory anti-idiotypic sera was restricted to syngeneic combinations, which suggests a potential role of autoanti-idiotypic antibodies in the regulation of the immune response. The anti-idiotypic antisera used here are apparently directed against gene products not associated with the strain 2 or strain 13 major histocompatibility complex.     

Naturally occurring anti-Kell stimulated by E. coli enterocolitis in a 20-day-old child

Anti-A and anti-K have been found in the serum of a 20-day-old child who had not been transfused but who was acutely ill with E. coli enterocolitis. Both antibodies are IgM proteins. The mother's serum does not contain either antibody and the anti-A and anti-K in the infant's serum are not of maternal origin. Both parents and the child are of the Kell phenotype K−k+. Stool cultures made from the child yielded E. coli O 125:B15, an uncommon B-variant pathogenic coliform. Cell-free preparations made from broth cultures of this organism have strong specific inhibitory activity against IgM anti-A and anti-K, and both antigens have been identified on the bacterial cells. At age 3 months the child had made a clinical recovery, stool cultures showed no pathogenic coliforms, and anti-A and anti-K were no longer detectable in her serum. These data indicate that absorption of metabolites with A− like and K−like activity produced by a pathogenic coliform in the intestinal tract were responsible for the appearance of apparent naturally occurring anti-A and anti-K in the child's serum.     

Depletion of CD8+ cells in human thymic medulla results in selective immune deficiency

CD8 molecules expressed on the surface of a subset of T cells participate in the selection of class I MHC antigen-restricted T cells in the thymus, and in MHC-restricted immune responses of mature class I MHC antigen-restricted T cells. Here we describe an immune-deficient patient with lack of CD8+ peripheral blood cells. The patient presented with Pneumocystis carinii pneumonia and was unable to reject an allogeneic skin graft, but had normal primary and secondary antibody responses. Examination of the patient's thymus revealed that the loss of CD8+ cells occurred during intrathymic differentiation: the patient's immature cortical thymocytes included both CD4+ and CD8+ cells while the mature medullary cells expressed the CD4 but not the CD8 protein on their surface. Northern blot and polymerase chain reaction analyses revealed the presence of CD8 alpha and beta mRNA in the patient's thymus but not in the peripheral blood. Both class I MHC antigen expression and the expressed TCR V beta repertoire are normal in this patient. These data are consistent with an impaired selection of CD8+ cells in the patient's thymus and support the role of the CD8 surface protein in thymic selection previously characterized in genetically manipulated and inbred mice.     

Antimicrobial synergism against Mycobacterium avium complex strains isolated from patients with acquired immune deficiency syndrome.

Pairs of 11 antimicrobial agents were tested in vitro for their ability to act synergistically against three strains of Mycobacterium avium complex isolated from patients with acquired immune deficiency syndrome. From the combinations tested, four drugs (ethambutol, rifampin, ciprofloxacin, and erythromycin) were selected for more extensive study against 20 strains of M. avium complex. The inhibitory and killing synergism obtained with combinations of two, three, or four drugs was assessed by determining the fractional inhibitory concentration index and fractional bactericidal concentration index. Inhibitory synergism occurred against 90 to 100% of the strains for all drug combinations in which ethambutol was included. Killing synergism occurred against 85 to 95% of the strains when ethambutol was used in combinations which included either rifampin or ciprofloxacin. However, killing synergism occurred against only 45% of the strains when drugs were tested at concentrations that can be obtained in patient serum. In other experiments, rifabutin (Ansamycin) gave results that were comparable to those obtained with rifampin. Clofazimine did not show synergistic killing activity at a concentration that is achievable in serum for any of the drugs tested. Our results indicate that there is considerable variability in the antimicrobial susceptibility of M. avium isolates obtained from patients with acquired immune deficiency syndrome. This variability could have significant impact on the clinical response to various therapies.     

Induction of IgG antibodies against GD3 ganglioside in rabbits by an anti-idiotypic monoclonal antibody.

Anti-idiotypic MAb were raised in syngeneic mice against a mouse MAb recognizing GD3 ganglioside (MAb R24). Two anti-idiotypic MAb, designated BEC2 and BEC3, recognized distinct determinants on MAb R24 that mapped near or within the GD3-binding site. New Zealand white rabbits, which express GD3 on normal tissues, were immunized with either BEC2, BEC3, or control MAb FLOPC-21. All rabbits developed high and equivalent titers of antibodies against mouse immunoglobulins. Immunization with BEC2 and BEC3 induced rabbit antibodies expressing R24 idiotype as demonstrated by their ability to inhibit BEC2 binding to R24. Antibodies (IgG and IgM) reacting with GD3 developed in five of eight rabbits immunized with BEC2 but not in rabbits immunized with BEC3 or with control MAb. Serum antibodies against GD3 did not cross-react with other gangliosides. These results show that MAb BEC2 can mimic GD3 ganglioside and can induce antibodies against GD3 ganglioside despite expression of GD3 on normal rabbit tissue.     

Studies on the in vitro formation of antibodies. III. Induction of primary and secondary immune response in vitro]

Peritoneal cells from normal, unimmunized mice (female NMRI, 28-32 gr) produced in vitro primary and secondary immune response after induction with the bacteriophage T2 6 hours or 7 day resp. after establishing the cultures. We confirmed the induction of a primary and secondary immunological response in vitro in the very same culture by the following data: 1. In vivo the donor animals were not in contact with the antigen used. We found neither the phage nor its host E. coli B in the gut of 97 mice investigated and no humoral antibodies against T2. The kinetics of humoral antibody production in vivo by different doses of T2 also showed that there are no related or identical antigen structures incorporated in our animals. 2. The T2 neutralizing activity in the culture medium after the first induction had the sedimentation constant of 19.7 +/- 2.3 S (n = 9) but the activity found after the second induction sedimented with 8.1 +/- 0.7 S (n = 10). 3. The primary activity was more sensitive to mercaptoethanol than the secondary. 4. Complement was bound by the complex T2 + neutralizing activity.