Monoclonal antibody to fungal glucosylceramide protects mice against lethal Cryptococcus neoformans infection.

Glucosylceramides (GlcCer) are involved in the regulation of Cryptococcus neoformans virulence. In the present study, we demonstrate that passive immunization with a monoclonal antibody to GlcCer significantly reduces host inflammation and prolongs the survival of mice lethally infected with C. neoformans, revealing a potential therapeutic strategy to control cryptococcosis.

Structure, cellular distribution, antigenicity, and biological functions of Fonsecaea pedrosoi ceramide monohexosides.

Monohexosylceramides (CMHs, or cerebrosides) have been reported as membrane and cell wall constituents of both pathogenic and nonpathogenic fungi, presenting remarkable differences in their ceramide moiety compared to mammalian CMHs. Current evidence suggests that CMHs are involved in fungal differentiation and growth and contribute to host immune response. Here we describe a structural diversity between cerebrosides obtained from different forms of the human pathogen Fonsecaea pedrosoi. The major CMH species produced by conidial forms displayed the same structure previously demonstrated by our group for mycelia, an N-2'-hydroxyhexadecanoyl-1-beta-d-glucopyranosyl-9-methyl-4,8-sphingadienine. However, the major cerebroside species purified from sclerotic cells carries an additional hydroxyl group, bound to its long-chain base. The structural difference between cerebrosides from mycelial and sclerotic cells was apparently not relevant for their antigenicity, since they were both recognized at similar levels by sera from individuals with chromoblastomycosis and a monoclonal antibody to a conserved cerebroside structure. Preincubation of fungal cells with anti-CMH monoclonal antibodies had no effect on the interaction of F. pedrosoi sclerotic cells with murine macrophages. In contrast to what has been described for other fungal species, sclerotic bodies are resistant to the antifungal action of anti-CMH antibodies. Immunofluorescence analysis showed that recognition of sclerotic cells by these antibodies only occurs at cell wall regions in which melanization is not evident. Accordingly, melanin removal with alkali results in an increased reaction of fungal cells with anti-CMH antibodies. Our results indicate that cerebroside expression in F. pedrosoi cells is associated with dimorphism and melanin assembly on the fungal cell wall.

Glucosylceramides in Colletotrichum gloeosporioides are involved in the differentiation of conidia into mycelial cells.

Glucosylceramides (GlcCer) were extracted from the plant pathogen Colletotrichum gloeosporioides and purified by several chromatographic steps. By using electrospray ionization mass spectrometry and nuclear magnetic resonance, GlcCer from C. gloeosporioides were identified as N-2'-hydroxyoctadecanoyl-1-beta-D-glucopyranosyl-9-methyl-4,8-sphingadienine and N-2'-hydroxyoctadecenoyl-1-beta-D-glucopyranosyl-9-methyl-4,8-sphingadienine. Monoclonal antibodies against these structures were produced and used as tools for the evaluation of the role of GlcCer in the morphological transition of C. gloeosporioides. In the presence of antibodies to GlcCer, the differentiation of conidia into mycelia was blocked. Since GlcCer is present in several plant pathogens, the inhibitory activity of external ligands recognizing these structures may be applicable in other models of fungal infections.

Antibodies to diverse lipids in the serum of patients with clinically cured leprosy and tuberculosis.

In this study we looked for the presence of antibodies to cardiolipin, cerebrosides, and whole lipids extracted from M. leprae, M. tuberculosis and M. habana, in the serum of patients with clinically cured lepromatous leprosy (sixteen) or tuberculosis (sixteen), 8 to 12 months after arresting the corresponding multi-drug therapy (MDT). Compared to healthy controls (sixteen), both leprosy and tuberculosis ex-patients had still significant levels of antibodies to the three mycobacterial lipids but no detectable levels of antibodies to cardiolipin or cerebroside lipids. Although leprosy and tuberculosis sera recognized the homologous mycobacterial lipids in a preferential fashion, all of them, on the average, reacted more strongly with the lipids of M. habana. This observation backs up, in a certain way, the proposition of using M. habana as a prospective vaccine for leprosy and tuberculosis.

Anti-Vel reactivity diminished by adsorption with rabbit RBC stroma.

BACKGROUND: An anti-Vel, nearly missed in antibody identification studies, and the effect of a commercially available rabbit RBC stroma (RESt, Immucor) adsorptions on eight anti-Vel sera are reported. Anti-Vel is an antibody to an antigen of high prevalence. CASE REPORT: A 48-year-old woman with chronic vaginal bleeding presented with a Hct of 14.7 percent. The transfusion service was not informed of her history of anti-Vel when she was transferred from another institution. Studies performed on an emergency request for transfusion were interpreted as a cold autoantibody as adsorption with a commercial source of RESt eliminated the reactivity. Stored anti-Vel sera were tested by titration studies before and after adsorption with commercial RESt. RESULTS: Serum from the index case did not react after adsorption with RESt at the transfusion service. Studies with the stored anti-Vel indicated antibody adsorption with four of four samples at immediate spin (IS) and room temperature (RT) phases, four of eight samples at 37 degrees C in albumin (ALB) phase, and four of eight samples at ALB-IgG-AGT phase. Variations in antibody reactivity were observed in the samples tested, but RESt adsorption diminished antibody reactivity in most samples. All eight stored sera demonstrated some reactivity in at least one phase after adsorption with RESt. CONCLUSION: Anti-Vel was completely or partially adsorbed by RESt. Caution should be used when interpreting cold agglutinins with this method. The manufacturer warns that uncommon alloantibodies may be adsorbed.

Forssman penta- and tetraglycosylceramide are xenoantigens of ostrich kidney and liver.

The heterophile antigens Galalpha1-->3Gal and N-glycolylneuraminic acid are the major obstacle to grafting mammal organs, especially from pig, to man. Lack of expression of these common xenoantigens by birds has raised interest in ostrich as a potential organ donor for xenotransplantation. Glycosphingolipids of ostrich liver and kidney were investigated for their carbohydrate determinants. Both organs were found similar in their glycolipid composition with three major species, mono-, di-, and pentaglycosylceramide. The pentaglycosylceramide was characterized as the Forssman antigen. In both organs, the ceramide portion was highly hydroxylated with prevalence of alpha-hydroxylated fatty acids, C18 phytosphingosine in kidney and C18 sphingosine in liver Forssman glycolipid. These data indicate that hydroxylation of kidney glycosphingolipids, which is found in mammals, has been maintained since the divergence of birds from other vertebrates. Characterization of a minor glycolipid as a Forssman tetraglycosylceramide built on the galabiosylceramide core indicates that the Forssman tetraglycosylceramide also exists in vivo. Its precursors, galactosyl- and galabiosylceramide, were characterized in kidney and liver. The Forssman antigen is the third heterophile antigen against which man raises natural antibodies. Its localization in the vascular endothelium and connective tissue makes ostrich an unpromising organ or cell donor for xenotransplantation to man.

The clinical significance of u-FCC, an antigen of anti-fucosylceramide antibody found in urine, in patients with gastric and colorectal carcinoma.

BACKGROUND: It has already been shown that the production of fucosylceramide, an aberrant glycolipid, is associated with neoplastic changes in human tissues. The authors of this study designed a sandwich radioimmunoassay (RIA) using a mouse monoclonal anti-fucosylceramide antibody, PC47H, designated as PC/PC RIA, and measured the level of u-FCC, an antigen of PC47H, in the urine of cancer patients. METHODS: The cohort comprised 41 patients with gastric carcinoma, 35 with colorectal carcinoma, 34 with other malignancies, 14 with cholelithiasis, 18 with gastric ulcer, and 110 healthy individuals. The u-FCC was quantified by PC/PC RIA. The cutoff value of u-FCC was obtained from the 110 healthy individuals, and the rates of positivity for gastric and colorectal carcinoma patients were evaluated. RESULTS: The rates of u-FCC positivity were 63% for patients with gastric carcinoma and 69% for colorectal carcinoma patients. The rate was only 1% (1/110) for the healthy individuals. The u-FCC value did not correlate with the values of either CA 19-9 or carcinoembryonic antigen (CEA). In a combination assay of u-FCC with CA 19-9 and CEA, the positivity rates were 84% for gastric carcinoma patients and 85% for colorectal carcinoma patients. CONCLUSIONS: Gastric and colorectal carcinoma patients have significantly high levels of u-FCC in their urine compared with normal individuals.

Sulphatide-binding properties are shared by serum amyloid P component and a polyreactive germ-line IgM autoantibody, the TH3 idiotype.

Serum amyloid P component (SAP) concentration was elevated in sera from leprosy patients, significantly so above endemic controls in lepromatous cases. In the sera of lepromatous leprosy (LL) patients who experienced an erythema nodosum leprosum (ENL) episode the SAP fell at the onset of ENL and remained low throughout, in two of three cases. Changes in SAP concentration parallel anti-sulphatide IgM concentrations. TH3, a monoclonal IgM germ-line antibody derived from a LL patient, and SAP share similar binding patterns. In this study we demonstrate binding to heparin and sulphatide. Moreover, SAP inhibited the binding of TH3 to sulphatide, as well as anti-sulphatide IgM found in a range of sera, and anti-sulphatide IgG in the only sera sample in which it was found. The observation that anti-TH3 idiotype monoclonal and polyclonal anti-SAP antibodies both inhibited the binding of TH3 and IgM in sera (but not IgG) to sulphatide without binding to sulphatide themselves further demonstrated similar binding specificities. The observations of similarity in binding reinforce ideas that SAP may function as a primitive opsonin, but the clear ability to inhibit binding of autoantibodies suggests that SAP may play a role in ameliorating tissue and particularly nerve damage in leprosy patients.

Autoantibodies to cerebroside sulphate (sulphatide) in leprosy.

Sera from 40 leprosy patients were screened for autoantibodies to cerebroside sulphate (sulphatide). Anti-sulphatide IgM in groups of patients with lepromatous (LL) and borderline (BL + BB + BT), but not with tuberculoid (TT) disease, were significantly elevated above the levels found in endemic control subjects. Eight-six percent (18 out of 21; mean 1.59 OD units) of LL, 33% (four out of 12; mean 1.08 OD units) of borderline and 13% (one out of eight; mean 0.69 OD units) of tuberculoid patients had anti-sulphatide IgM in their sera above a cut-off value of 2 s.d. above the mean value (0.66 OD units) for control sera. Elevated anti-sulphatide IgG was detected in only one patient's serum, an individual with LL disease. The level of anti-sulphatide IgM was strongly correlated to expression of the TH3 idiotype, an idiotype previously defined by a human MoAb that bound Mycobacterium leprae phenolic glycolipid, Klebsiella capsular polysaccharide, polynucleotides and human tissues. The purified, TH3 MoAb was found in this study to bind sulphatide, but not cholesterol-3-sulphate or cerebroside. It is suggested that anti-sulphatide IgM is elevated in leprosy, in relation to the bacterial load. Anti-sulphatide IgM fell at the onset of erythema nodosum leprosum (ENL) reaction, consistent with the deposition of serum antibodies, and thus may play a part in pathology during periods of inflammation, particularly in multibacillary patients.

Immunoreactive fucosylceramide as a B-cell differentiation marker.

The reactivity of PC47H, a monoclonal antibody (mAb) directed against fucosylceramide, with cells of lymphoid lineage was examined. Immunoreactive fucosylceramide (FC) was recognized only in pokeweed mitogen (PWM)-stimulated B blasts, plasma cells and germinal center cells. mAb PC47H did not react with T cells at different stages or with peripheral blood B cells. Furthermore, FC was expressed abundantly in blastic cells of B-cell lymphoma, multiple lymphoma and myeloma cell lines KMS-12-BM and KMS-12-PE. In other words, FC was expressed more strongly in mature than in immature B cells. Immunoelectron microscopy showed that FC was located in the plasma membrane and rough endoplasmic reticulum. mAb PC47H can therefore be used as a unique B-cell differentiation marker for study of B-cell activation and differentiation and clonal analysis of lymphoid malignancies.

Antibodies specific for the lipid-bound form of myelin basic protein during experimental autoimmune encephalomyelitis.

On the hypothesis that myelin basic protein isolated with surrounding lipids may constitute an autoantigen in demyelinating diseases, we studied the antibody response to the lipid-free and lipid-bound form of myelin basic protein during the course of experimental autoimmune encephalomyelitis induced in rats with either form of protein. Immunization with the lipid-bound form of myelin basic protein induced high titres of antibodies directed to the protein, accompanied by no antibodies to cerebroside 30 days after immunization. Antibodies specifically directed to the lipid-bound form of myelin basic protein were revealed after removal of antibodies recognizing the delipidated myelin basic protein. Anti lipid-bound myelin basic protein antibodies could already be detected at day 10 post-immunization, reaching a maximum at day 20 post-immunization. Demonstrations of antibodies entirely specific for the lipid-bound form of myelin basic protein suggests that this molecule may present epitopes not to be found in its already extensively studied primary structure, possibly the result of conformational changes following lipid binding.

Establishment and characterization of a mouse monoclonal anti-fucosylceramide antibody, PC47H.

A novel mouse monoclonal anti-fucosylceramide antibody was established by using neutral glycolipids from a human pancreas cancer tissue as the immunogen. Mice were immunized with the neutral glycolipids in the form of liposome-containing lipid A. Mouse monoclonal antibodies were screened with enzyme-linked immunosorbent assay and by thin layer chromatography-immunostaining. The latter technique showed that a mouse monoclonal antibody, designated PC47H, specifically reacts with a ceramide-monoglycoside fraction of the neutral glycolipids. The effects of various monosaccharides on the reactivity of PC47H with the neutral glycolipids were tested, and it was found that only fucose was able to inhibit the binding of PC47H to the neutral glycolipids. We also examined the direct binding activity of PC47H against galactosylceramide, glucosylceramide, fucosylceramide, and ceramide. This showed that the antigen specificity of PC47H was exclusively directed against fucosylceramide. In thin layer chromatography-immunostaining experiments with neutral glycolipids prepared from various human tissues, we observed that fucosylceramide was highly expressed in human colon and gastric cancer tissues. PC47H recognized the human adenocarcinoma cell lines of colon, stomach, pancreas, and lung but did not react with other tumor cells or with several nontumorous human cells.

Elevated cerebroside antibody levels in human visceral and cutaneous leishmaniasis, Trypanosoma rangeli infection, and chronic Chagas' disease.

A natural cerebroside (antiC) IgM antibody was found at relatively high levels in the serum of every healthy individual studied. The reactivity of the antibody was assessed by using highly purified bovine brain galactocerebroside (galC) or human glucocerebroside (gluC) as antigen. The importance of fatty acid moiety of galC in antigen-antibody reaction was demonstrated by low immunoreactivity using 1-beta-D-galactosyl sphingosine (GS) as antigen and by the absence of absorption to GS-bearing liposomes. The presence of alpha-hydroxy and non-hydroxy fatty acids in galC did not modify its immunoreactivity. Cerebroside antibody binding activity was only partially blocked by 0.5 M galactose or alpha- and beta-methylgalactopyranoside, suggesting poor specificity of antiC for a specific glycosidic residue or linkage. In fact, liposome-bearing gluC absorbed galC. AntiC did not adsorb on rabbit, guinea pig, or human erythrocytes (RBC), but absorbed strongly on rat RBC. Elevated antibody levels were found in 57% of Kala azar patients, 56% of Trypanosoma rangeli-infected patients, 30% of chronic chagasic patients, and 20% of cutaneous leishmaniasis patients, but were not found in 16 other inflammatory or infectious diseases studied. This suggests an association between Kinetoplastida infection and elevated levels of antiC, with parasitic galC acting probably as a highly immunogenic antigen. A possible role of anti-galC in the neuropathological symptoms of Chagas' disease and in the control of parasitemia levels in T. rangeli-infected individuals is discussed.

Autoantibodies to brain lipids in schizophrenia.

Serum IgG antibody to brain lipids was measured with an ELISA technique in 38 schizophrenic patients and 22 normal subjects. There were no significant differences between groups. The authors discuss methodological differences between this study and studies with positive findings.

Dependence of the surface expression of the glycolipid cerebroside sulfate on its lipid environment: comparison of sphingomyelin and phosphatidylcholine.

The influence of the membrane lipid environment on the reactivity with antibody of the acidic glycolipid cerebroside sulfate (CBS) was examined by using a spin membrane immunoassay. Fewer antibodies in a polyclonal anti-CBS antiserum recognized the antigen in a bovine brain sphingomyelin/cholesterol (SM/CHOL) environment than in dipalmitoylphosphatidylcholine/cholesterol (DPPC/CHOL). Changes in the CBS ceramide group appeared to have less influence on antibody recognition of CBS in SM/CHOL than in DPPC/CHOL [Crook et al. (1986) Biochemistry 25, 7488-7494]. Although the fatty acid chain length of phosphatidylcholine strongly influences CBS recognition, the fatty acid chain length of sphingomyelin had only a moderate effect on CBS recognition and did not account for the decreased recognition in SM compared to in DPPC. Inhibition studies revealed that the antibodies which recognize CBS in SM/CHOL (S antibodies) form a population distinct from those which recognize CBS in DPPC/CHOL (P antibodies). The specificity of the P and S antibodies was examined further by comparing the efficacy of various substances, which share chemical features with the components of CBS in a SM/CHOL or DPPC/CHOL environment, to inhibit lysis of liposomes containing CBS. Intact CBS, cholesterol, and a phosphocholine lipid, at certain antigen densities, were required for optimal recognition of the antigen, especially by the P antibodies, suggesting that a complex of all three lipids in a multivalent array may be recognized by these antibodies. The S antibodies may recognize a smaller complex or monomers of CBS.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutral glycosphingolipids of the globo-series characterize activation stages corresponding to germinal center B cells.

The neutral glycosphingolipid (GSL) globotriaosylceramide (Gb3) of the globo-series was recently defined as the CD77 antigen. This B cell-associated antigen is characterized by its specific expression on germinal center B cells. In order to study the potential relation of the CD77 antigen and other GSLs to B cell activation we have performed a comprehensive analysis of the synthesis and expression of neutral GSL in tonsillar B lymphocytes. Monoglycosylceramide (GL1) and lactosylceramide (LacCer) comprised the largest portion of GSL in tonsillar B lymphocytes as detected by HPLC analysis. GSLs of the globo-series Gb3 and globotetraosylceramide (Gb4), were found in smaller amounts. Since other GSLs, like gangliotriaosylceramide (Gg3) and gangliotetraosylceramide (Gg4), could only be detected using highly sensitive antibody reactions, we assume that these GSLs occur in B cells only in minor amounts. When tonsillar B cells were density fractionated on Percoll, the light density cells, which correspond to activated cells, contained and expressed more of both globo-GSLs than cells in the higher density fraction. When the dense fraction of tonsillar B cells was activated in vitro by anti-mu/BCGF, synthesis of GL1, LacCer, Gb3, and Gb4 was biphasic, with maxima at 12 and 84 h. Surface expression of the CD77 antigen on the denser cells was strongly induced by anti-mu/BCGF during the first 24 h of cultivation followed by a rapid decline thereafter, mimicking synthesis. PMA treatment of this cell fraction caused an even stronger expression of the CD77 antigen, which lasted over 48 h of cultivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibody to galactosylceramide: discrimination of structural difference in the ceramide moiety.

A mouse monoclonal antibody (mAb) was developed against monohexaosylceramide. This mAb differentially reacted on thin-layer chromatograms with 3 types of galactosylceramide (GalCer) obtained from bovine brain. Structural analysis of the 3 glycolipids revealed that they consisted of the same galactose and sphingosine but of apparently different fatty acids. Among the GalCers, the mAb reacted with teh two GalCers which contained alpha-hydroxy fatty acids, but not with GalCer composed of nonhydroxy fatty acids. These findings suggest that not only that the mAb discriminated the fatty acid composition in the ceramide moiety of GalCer, but also that the ceramide structure defines the immunological epitope as it is known to do for the carbohydrate moiety of glycosphingolipid.

Immunological studies of the pathogenesis of multiple sclerosis. Cell-mediated cytotoxicity by peripheral blood lymphocytes against basic protein of myelin, encephalitogenic peptide, cerebrosides and gangliosides.

Cell-mediated cytotoxic reactions against myelin basic protein (MBP), encephalitogenic peptide, cerebrosides and gangliosides were studied in 165 MS cases. The cytotoxicity, which is detectable only in the autologous system, is mediated by T lymphocytes bearing antigens reactive with antibody OKT8. The cytotoxicity is highest during active MS regardless of whether it is relapsing or chronic progressive. During inactive MS cytotoxicity is significantly less and remains virtually unchanged at a low level over long periods. The degree of cytotoxicity is thus, predominantly, dependent on the activity stage of the disease. Further, there is a correlation with the severity of the clinical deficiencies. The pathogenetic significance of cytotoxic reactions can be recognized by the close correlation between the stage and course of MS, which can be demonstrated both statistically and individually.