Defective resistance to Plasmodium yoelii in CBA/N mice.

The role of B lymphocytes in resistance to malaria was studied in defective and normal F1 mice derived from CBA/N mice, a strain with an X-linked B cell defect. When infected with normally nonlethal Plasmodium yoelii, immune defective F1 male mice had higher parasitemias and more prolonged infections than normal F1 mice, as well as a 50% mortality rate. Before infection the plasma levels of IgM and IgG were lower in defective F1 males than normal F1 mice. The polyclonal IgM and IgG responses of infected abnormal F1 mice were delayed and lower in absolute magnitude than those of normal F1 mice. Furthermore, specific IgM and IgG anti-plasmodial antibody titers, as determined by radioimmunoassay, were depressed on day 12 in the defective F1 males. Although IgG titers approached those of the normal F1 mice on day 19, defective F1 male IgM titers remained depressed. These data demonstrate that an X-linked gene that affects B cell function influences malarial resistance in mice, presumably via a decreased specific IgM response, and the slow development of a specific IgG response to P. yoelii infection.     

Lentinula edodes produces a multicomponent protein complex containing manganese (II)-dependent peroxidase, laccase and beta-glucosidase

Haemozoin, the malaria pigment, regulates the synthesis of several host cytokines and has been found to be associated with the disease severity. Here we describe that malarial patients produce a significant amount of anti-haemozoin IgM antibodies. Levels of these antibodies were higher among the complicated Plasmodium falciparum cases compared to the non-complicated P. falciparum group and Plasmodium vivax patients. The P. falciparum haemozoin also induced the synthesis of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) by the monocytes of the healthy individuals, but the production of these cytokines by the monocytes was inhibited in the presence of the anti-haemozoin IgM antibodies. Therefore, it seems that the host produces these antibodies (mainly IgM types) during malarial infection that can influence the progression of the disease by inhibiting the production of cytokines.     

Normal human sera contain antibodies directed at Fab of IgA

Serum samples from 26 normal volunteers were evaluated by isotype-specific ELISA for the presence of IgG and IgM antibodies directed at IgA. Although there were wide variations in antibody levels, anti-IgA antibodies of both isotypes were found in all individuals tested. The anti-IgA activity was detected against a variety of polymeric and monomeric IgA1 and IgA2 myeloma proteins containing both kappa and lambda light chains. By using Fab and Fc fragments generated by incubation of an IgA1 myeloma protein with IgA1 protease, it was shown that the anti-IgA activity was specific for the Fab portion of the IgA molecule. It was also demonstrated that the serum of two individuals contained both IgG and IgM activity directed at autologous affinity-purified IgA. IgM antibody levels against both whole IgA and Fab of IgA were significantly higher than IgG antibody levels. Cells producing anti-IgA antibodies of both isotypes were detected in lipopolysaccharide-stimulated human spleen.     

A protective monoclonal antibody with dual specificity for Plasmodium falciparum and Plasmodium berghei circumsporozoite proteins.

An IgM monoclonal antibody (Mab 36) which reacts with the circumsporozoite (CS) proteins of both P. falciparum and P. berghei was isolated from Plasmodium falciparum sporozoite-immunized mice. In assays of biological activity, Mab 36 induces the CS precipitation reaction with live sporozoites and blocks the invasion of hepatoma cells by sporozoites in vitro at concentrations much lower than those observed for previously reported CS protein-specific monoclonal antibodies. Mab 36 also provided complete protection against P. berghei sporozoite challenge in mice at low doses. Linear epitope mapping revealed that the epitope specificities recognized by Mab 36 are completely encompassed by other monoclonals previously shown to be associated in vivo with protection against P. falciparum or P. berghei sporozoite infection. These results suggest that the ability to make high-affinity IgM antibody to specific CS protein repeat epitopes may be important for eliciting protection against malarial infection.     

Analysis of the patterns of inheritance of splenomegaly and serum IgM levels in the Watut of Papua New Guinea

Hyperreactive malarious splenomegaly (HMS) reflects abnormal immune responses to malarial infection. The central question is whether HMS results from unusual patterns of malarial infection or from immune incompetence in the host. Family distributions of two features of the syndrome, splenomegaly and excessively high IgM levels, have been examined in a Papau New Guinea population in which HMS is exceptionally common. Segregation analysis of spleen grade shows that a major sex-linked gene controls hyperresponsiveness to malaria. This finding is supported by additional segregation analysis, which shows that an autosomal locus cannot account for a significant proportion of variation in spleen grade, and by path analysis, which rejects a model that assumes that parents contribute equally to the child's genotype. The sex-linked gene contributing to HMS was not mediated through sex linkage of a major gene for IgM concentrations, as shown by segregation analysis. It has yet to be determined whether this pattern of inheritance also applies to HMS occurring sporadically in other less severely affected populations. The applicability of these findings to the general variability in "normal" IgM responses to malaria also remains to be established.     

Neonatal suppression with anti-Ia antibody. III. In vivo responses to the type 2 antigen TNP-Ficoll

We studied the response to thymus-independent type 2 (type 2) Ag in mice suppressed from birth with anti-Ia antibody. Although these mice have significantly reduced numbers of surface IgM+ cells and reduced or absent levels of Ia-restricted Th cell activity, their IgM antibody response to the type 2 Ag TNP-Ficoll was unaffected whereas that to the prototypic thymus-dependent Ag SRBC was predictably eliminated. These data suggest that an in vivo antibody response can be made to type 2 Ag in the absence of Ia-dependent cellular interactions. The surface IgM+IgD-Ia- B cells that are found in the anti-Ia antibody-suppressed mouse may represent an expanded population of Ia-independent, type 2 Ag-sensitive B cells normally present as a smaller proportion of the splenic lymphocyte population. Thymus-dependent responses, which have been shown to have an absolute requirement for an Ia-dependent interaction, are absent in these animals.     

Circulating and tissue-bound immune complex formation in murine malaria.

Immune complex formation during Plasmodium berghei infection of OF1 mice was investigated. Circulating immune complexes (CIC) were detected by the Clg-binding assay and the conglutinin-binding solid-phase assay in lethal or drug-limited infections. CIC appeared on day 9 of infection, peaked on day 11, and disappeared only after complete cure of the infection. Analysis of the immune complexes detected by the Clq-binding assay revealed the following characteristics: sedimentation coefficients of 13S to 21S, resistance to DNAse, and selective removal by filtration through protein A bound to Sepharose. Glomerular deposits of IgM preceded the appearance of CIC, whereas deposits of IgG and C3 were concomitant with the appearance of CIC. Tissue-bound immunoglobulins were also found in the choroid plexus. The appearance of anti-malarial antibodies and malarial antigens in the serum was closely associated with a depression of C3 levels and the presence of CIC. Drug treatment was followed by normalization of C3 levels, and clearance of both CIC and malarial antigens.     

Seroepidemiological survey for antibody to Borrelia burgdorferi in cows.

Antibody to Borrelia burgdorferi was examined in 380 healthy and 38 clinical cases of cows from Hokkaido and Shizuoka in Japan. In healthy animals, IgG and IgM antibody to B. burgdorferi HO14 strain were found in 44 cows (14.6%) and 24 cows (8.0%) from Hokkaido. In contrast, antibody-positive case was not observed except for only 1 case which was IgM positive (1/79: 1.3%) in cows from Shizuoka. Mean antibody levels of healthy animals in Hokkaido and Shizuoka were 0.651 and 0.263 (IgG antibody to HO14 strain), 0.642 and 0.169 (IgG to HP3 strain), 0.613 and 0.367 (IgM to HO14 strain) and 0.582 and 0.286 (IgM to HP3 strain). The differences of the antibody levels between cows from Hokkaido and Shizuoka were significant. Seasonal difference was found in seropositive cows from Hokkaido. The rate of seropositive cows was high in summer (23.4% in June and 11.8% in July) but low in winter (0% in January and February). The pattern was discussed to be associated with activation of ticks. One of 4 cows with arthritis showed significantly higher IgG antibody level than that of healthy cows and cows with some disease, although the serum was collected from Shizuoka where antibody-positive animals for B. burgdorferi were rare among healthy cows. This high IgG antibody may suggest that the arthritis of such cows was caused by infection with B. burgdorferi. Two of 7 cows with unclassified abortion showed positive antibody reaction in Hokkaido. These cases, however, may not be related to the B. burgdorferi infection because the positive rate was similar to those of healthy cows in the same season.     

Defective vaccine-induced immunity to Schistosoma mansoni in P strain mice. I. Analysis of antibody responses

Inbred P4 strain mice have previously been shown to be uniquely defective in their resistance to challenge infection induced by irradiated cercariae of Schistosoma mansoni. To assess whether the low levels of resistance developed by vaccinated P mice could be due to a defective antibody response, we compared the anti-schistosomulum antibody responses in vaccinated P animals with those occurring in vaccinated C57BL/6J (B6) mice, a strain that consistently develops high levels of resistance to challenge infection. Our results indicate that vaccinated P mice develop levels of total anti-schistosomulum antibodies that are significantly lower than those occurring in B6 mice for at least 15 wk after immunization, with the exception of the fifth week, at which time the responses are indistinguishable. Further analysis revealed that the defect in P strain antibody response occurs specifically in the IgM isotype and that specific IgM levels in P mice are less than one-half the levels in B6 mice at every time point examined. In contrast, no differences in total IgM immunoglobulins were evident when sera from normal (nonvaccinated) P and B6 mice were compared. P mouse anti-schistosomulum IgG antibody responses reached the same levels as those observed in B6 mice by 5 wk after vaccination. However, a much faster decay in IgG antibody levels occurred after this time point in P animals. No differences were observed when the levels of anti-schistosomulum antibodies occurring in each of the major IgG isotypes (IgG1, IgG2a, IgG2b, IgG3) were compared in sera from P and B6 mice vaccinated 4 wk previously. Similarly, vaccinated P and B6 mice were found to mount indistinguishable IgG anamnestic responses after challenge infection. Finally, no differences between vaccinated P and B6 mice were observed when immediate (30 min) skin test and mast cell degranulation responses to a soluble schistosome antigenic preparation were compared. The above findings suggest that P strain mice have a specific defect in their ability to mount IgM antibody responses after immunization with irradiated cercariae. The possible contribution of this defect in IgM response to the decreased resistance of vaccinated P mice to challenge infection is discussed.     

Immunoglobulin G response against 10-kDa and 65-kDa heat-shock proteins in leprosy patients and their household contacts

Abstract We measured antibody responses to recombinant Mycobacterium leprae 65-kDa (rML65) and 10-kDa (rML10) by indirect ELISA in sera from leprosy patients, household contacts and healthy controls in a leprosy-endemic area in the north east of Argentina. Serum antibody levels to those antigens were correlated with IgM anti-phenolic glycolipid I (PGL-I) levels, with bacterial index and the period of time under chemotherapy. Bacterial index positive (BI⁺) patients showed higher mean values when compared with BI negatives (BI⁻). Among lepromatous patients a positive correlation was observed between IgG antibody responses to both recombinant antigens and IgM antibody response to PGL-I. Anti-rML10 test detected a higher percentage of positive/total than anti-rML65 in all leprosy groups and healthy contacts. Bacterial load, leprosy clinical form and the time under chemotherapy were factors which could influence levels of the antibody response. The contribution of these antibody studies for a precise and early diagnosis in leprosy is discussed.     

Protection and recovery in influenza virus-infected mice immunosuppressed with anti-IgM

BALB/c mice, immunosuppressed from birth with goat anti-mouse IgM, were able to recover from influenza virus infection in the absence of detectable serum and nasal antibody. Recovery was delayed a few days when compared with control animals. Antibody-deficient mice, that had recovered from an initial influenza virus infection, i.e., convalescent mice, were subsequently rechallenged with homologous influenza virus in order to study the importance of nasal and serum antibody in prevention of infection. Convalescent mice were susceptible to reinfection when nasal and serum antibody were not detectable. The mice were resistant to reinfection when serum and/or nasal antibody was detectable by radioimmunoassay. Normal mice that were passively immunized with high titer mouse anti-influenza virus serum were susceptible to challenge with homologous influenza virus. The serum antibody levels in these mice were higher than most of those found in the immune convalescent mice suppressed with anti-IgM, thereby suggesting that the serum antibody, found in convalescent suppressed mice, is not protective. We conclude that 1) mice can recover from influenza virus infection in the absence of detectable levels of nasal and serum antibody, thus indirectly confirming the role of cell-mediated immunity in recovery; 2) serum IgM, IgG2A, IgG2B, IgG3, and probably IgG1 antibody levels are not responsible for protection against influenza virus infection of the upper respiratory tract; and 3) nasal IgA antibody correlates best with protection against reinfection of the upper respiratory tract, but some other locally protective agent cannot be excluded.     

Effect of cold exposure on the metabolism of immunoglobulins in rabbits.

The effect of low environmental temperature on the metabolism of IgG and IgM was examined in unimmunized rabbits. The half-lives of both IgG and IgM were less in animals kept at 4 degrees C for 6 weeks than in animals kept at 22 degrees C. Serum concentration of IgM and GG were unaltered by cold exposure but intravascular pool sizes tended to increase as a consequence of an expanded serum volume. Fractional turnover rates of both IgM and IgG were greater in cold-exposed animals. At both 4 degrees C and 22 degrees C, the fractional catabolic rate of IgM was independent of its serum concentration whereas that of IgG was correlated directly with its serum concentration. Absolute turnover of both IgM and IgG was accelerated by cold exposure. It is suggested that increased synthesis of immunoglobulin could account for the higher levels of antibody reportedly found in cold-exposed rabbits.     

Lipid antigens derived from erythrocytes infected with Plasmodium berghei

Lipids were extracted from red blood cells infected with Plasmodium berghei, from the membranes of infected red cells and from free parasites. A radioimmunoassay was used to detect antibodies to these lipids in sera from convalescent and immune rats. Most of the antigenic activity could be attributed to the parasite although some activity was found in lipids isolated from the membranes of infected red blood cells. Absorption studies showed that the binding was specific for malarial lipid antigens. Immune sera showed no cross-reactivity with lipids from red blood cells of non-infected rats. However, sera from non-infected control rats showed low levels of cross-reactivity with the parasitized red cell-derived lipids. Levels of anti-lipid antibodies were directly correlated with the progress of the infection. The highest antibody level occurred when the parasitaemia reached zero. The malarial lipids had no effect on lymphoblast transformation of immune splenocytes in vitro. However, liposomes prepared from either malarial or non-specific lipids caused an increased response to antigen by the blast cells.     

B1 B cell numbers and antibodies against phosphorylcholine and LPS are increased in IL-6 gene knockout mice

Peritoneal cavity cells were isolated from IL6-gene knockout (IL6(-/-)) and wild-type mice and stained for expression of IgM, CD5, and CD23. B1 cell (IgM(+)/CD23(-), CD5(+)/IgM(+)) numbers were increased twofold in IL6(-/-) mice compared to normals while IgM(+)/CD23(+) (B2) cell numbers were reduced threefold. Intestinal antibody levels were also determined for both total immunoglobulin and phosphorylcholine (PC)-specific and LPS-specific antibody following oral challenge with attenuated Salmonella typhimurium. Total immunoglobulin levels (IgM, IgG, and IgA) were reduced 60-80% in intestinal secretions of IL6(-/-) mice compared to wild-type controls; however, PC-specific antibody was significantly higher in IL6(-/-) mice. Anti-LPS antibodies were also three- to sevenfold higher in IL6(-/-) mice compared to controls following Salmonella challenge. These data suggest that in IL6(-/-) mice the development of mucosal B2 cells is impaired but that intestinal B1 cells responding to microbial antigens such as PC and LPS develop normally and are fully functional.     

The characteristics of the antibody response of animals immunized with components of the surface structures of Francisella tularensis

Antibody formation in animals immunized with one of the components of F. tularensis surface structures was studied. The time course of antibody formation in 20 hamadryas baboons was studied in the passive hemagglutination (PHA) test, microagglutination (MA) test, and indirect enzyme immunoassay, used for the determination of IgG, IgA and IgM antibodies. The character of antibody response in the animals immunized with components of F. tularensis surface structures (S-complex) and with live tularemia vaccine was compared. The study revealed that immunization with the S-complex induced the formation of antibodies detected by all three methods. Antibody formation to the S-complex was found to be dose-dependent. With the increase of the injected dose of the S-complex, antibody titers determined in the PHA test decreased and those determined in the MA test increased, which was seemingly due to the induction of antibodies differing in their isotypes. After immunization with the S-complex the levels of IgG antibodies were lower and the levels of IgM antibodies by day 28 after immunization higher than after the injection of live tularemia vaccine.     

Characterization of the immunodeficiency of RIIS/J [corrected] mice. I. Association with the CD5 (LY-1) [corrected] B cell lineage

RIIIS/J mice produce low antibody responses to several polysaccharide Ag of bacterial origin. They have low levels of serum IgM and IgG3 and high levels of serum IgG2a and IgG2b. Low serum IgM and IgG3 have been attributed to a low frequency of CD5 (Ly-1) B cells, which play an important role in the production of natural antibodies. Indeed, RIIIS/J mice have a low frequency of CD5 (Ly-1)+, IgM bright+, Ly-5 (B220)dull+ (i.e., CD5 (Ly-1) B) cells in their peritoneum. RIIIS/J mice treated with LPS produce a low anti-bromelain-treated mouse RBC splenic plaque-forming cell response and a normal anti-mouse transferrin splenic PFC response. Those data are compatible with the fact that CD5 (Ly-1) B cells contain the precursors of B lymphocytes secreting anti-bromelain-treated mouse RBC antibody. However, they have a higher frequency of IgM bright+, Mac-1+ cells in their peritoneum. These cells represent the CD5 (Ly-1) "sister population" of CD5 (Ly-1) B cells described by others. This suggests that characteristics usually associated with the CD5 (Ly-1) lineage are applicable only to the CD5 (Ly-1)+ Mac-1+ IgM+ population, but not the related CD5 (Ly-1)- Mac-1+ IgM+ population. RIIIS/J mice should thus prove a valuable model to study the CD5 (Ly-1) B cell lineage.     

Efficacy of bi-valent whole cell inactivated bacterial vaccine against Motile Aeromonas Septicemia (MAS) in cultured catfishes (Heteropneustes fossilis,Clarias batrachus and pangasius pangasius) in Bangladesh

The Motile Aeromonas Septicemia (MAS) is an important disease of cultured catfishes (Heteropneustes fossilis, Clarias batrachus and Pangasius pangasius), caused by different species of Aeromonas bacteria which have been documented to be higher death rates (≤70%) in Bangladesh since 2016. Present study was conducted to develop bi-valent vaccine using A. hydrophila and A. veronii, and to validate their efficacy via intra-muscular (IM) and oral-routes of immunization in selected species of fishes. Brood fishes of the three species were immunized with three doses of inactivated vaccine (10⁷ CFU /2.3 mg/ml). Hematological parameters of brood fishes and antibody levels (IgM) of broods, their larvae and eggs were determined by ELISA. Additionally, Relative Percent Survivability (RPS) and the IgM levels of the larvae after challenge with virulent A. hydrophila and A. veronii were also evaluated. Findings of this study showed that the lymphocytes, monocytes, granulocytes counts and antibody (IgM) titre of brood fishes, larvae and eggs from the vaccinated fishes were found significantly higher (p< 0.05) compared to the un-vaccinated control groups. Alternatively, antibody levels (IgM) in the larvae of vaccinated group of brood fishes fed with antigen coated feed was exhibited to be remarkably higher (p< 0.05) than the antigen non-fed group. The RPS of larvae of Shing (91.24 ± 2.00%), Magur (88.09 ± 2.88%) and Pangas (93.17 ± 1.52%) was found to be higher in the larvae at 20-day age of vaccinated group compared to non-vaccinated brood fishes group. Findings of this study indicated that the active immunization of brood fishes followed by oral immunization of their larvae feeding with antigen coated feed showed synergistic effect in protecting cultured Shing, Magur and Pangas fishes from frequent attack with Aeromonas spp at any age of their lifetime.     

Tropical Splenomegaly Syndrome in a Rwandan Kindred in Uganda

Twenty members of an immigrant Rwandan kindred were all found to have tropical splenomegaly syndrome compared with 29 out of 50 matched neighbour controls. Splenomegaly among the controls tended to cluster within families. IgM levels were significantly raised in the kindred compared with the control subjects without splenomegaly but were similar to those of neighbours with splenic enlargement. We advance a hypothesis that tropical splenomegaly syndrome results from the production of circulating immune complexes in individuals genetically predisposed to produce an IgM antibody response.     

Plasmodium chabaudi chabaudi: B-1 cell expansion correlates with semiresistance in BALB/cJ mice

The largest obstacle impeding the development of an effective malaria vaccine is the incomplete understanding of how the immune response is regulated during infection. B-1a cells, a poorly understood subcategory of B lymphocytes, produce nonpathologic autoantibodies of low affinity which have been shown to have distinct immunoregulatory capabilities. What the exact activity of B-1a cells are during the course of malaria has yet to be determined. By use of flow cytometry, it was observed that B-1a cells significantly expand by day 3 postinfection in the spleen and peritoneum of Plasmodium chabaudi chabaudi semiresistant BALB/cJ mice, but not until day 8 postinfection in the spleen of P. chabaudi chabaudi fully susceptible BALB/cByJ mice. The activation of B-1a cells was also demonstrated by the measurement of natural autoantibody IgM production from the serum and cultured peritoneal B-1a cells. Infected semiresistant BALB/cJ mice generated higher levels of anti-ssDNA IgM antibodies than infected fully susceptible BALB/cByJ mice. The preliminary data presented here suggest a possible roll of B-1 cells in contributing to the successful survival of murine malarial infection.     

Competition between Serum IgG,IgM, and IgA Anti-Glycan Antibodies

Anti-glycan antibodies are an abundant subpopulation of serum antibodies with critical functions in many immune processes. Changes in the levels of these antibodies can occur with the onset of disease, exposure to pathogens, or vaccination. As a result, there has been significant interest in exploiting anti-glycan antibodies as biomarkers for many diseases. Serum contains a mixture of anti-glycan antibodies that can recognize the same antigen, and competition for binding can potentially influence the detection of antibody subpopulations that are more relevant to disease processes. The most abundant antibody isotypes in serum are IgG, IgM, and IgA, but little is known regarding how these different isotypes compete for the same glycan antigen. In this study, we developed a multiplexed glycan microarray assay and applied it to evaluate how different isotypes of anti-glycan antibodies (IgA, IgG, and IgM) compete for printed glycan antigens. While IgG and IgA antibodies typically outcompete IgM for peptide or protein antigens, we found that IgM outcompete IgG and IgA for many glycan antigens. To illustrate the importance of this effect, we provide evidence that IgM competition can account for the unexpected observation that IgG of certain antigen specificities appear to be preferentially transported from mothers to fetuses. We demonstrate that IgM in maternal sera compete with IgG resulting in lower than expected IgG signals. Since cord blood contains very low levels of IgM, competition only affects maternal IgG signals, making it appear as though certain IgG antibodies are higher in cord blood than matched maternal blood. Taken together, the results highlight the importance of competition for studies involving anti-glycan antibodies.