Direct evidence for the role of COOH terminus of mouse mammary tumor virus superantigen in determining T cell receptor V beta specificity

It has recently been shown that open reading frames in the 3' long terminal repeats of mouse mammary tumor viruses encode superantigens. These viral superantigens (vSAGs) stimulate most T cells expressing appropriate V beta s almost regardless of the rest of the variable components of the T cell receptors (TCR) expressed by those cells. vSAGs produce a type II integral membrane protein with a nonessential short cytoplasmic domain and a large glycosylated extracellular COOH-terminal domain, which is predicted to interact with major histocompatibility complex class II molecules and the TCR. The transmembrane region of vSAG also has an internal positively charged lysine residue of unknown significance. A set of chimeric and mutant vSAG genes has been used in transfection experiments to show that only the extreme COOH-terminal portion of vSAGs determine their TCR V beta specificities, and to show that the lysine residue in the transmembrane domain is not essential for the function of vSAG.

Allele-specific B pocket transplant in class I major histocompatibility complex protein changes requirement for anchor residue at P2 of peptide

To investigate the role of an anchoring pocket in allele-specific peptide presentation by a major histocompatibility complex class I molecule, we "transplanted" a B pocket from HLA-A*0201 into HLA-B*2705 by site-directed mutagenesis. The resulting protein, designated B27.A2B, binds a different set of endogenous peptides than B*2705 as evidenced by complete loss of allorecognition as well as restored expression in the antigen processing-defective mutant cell line T2. B27.A2B also fails to present an HLA-B27-restricted influenza virus peptide [nucleoprotein (383-391)] to cytotoxic T lymphocytes (CTLs). However, substitution of leucine, the predominant P2 anchor residue in A*0201-restricted peptides, for arginine, the P2 anchor in nucleoprotein-(383-391) and other B*2705-restricted peptides, restores recognition of B27.A2B by the same B*2705-restricted peptide-specific CTLs. These results demonstrate that a dominant polymorphic pocket in a class I molecule, through interaction with the anchor residue of an antigenic peptide, can distinguish among peptides differing by only a single amino acid and thus determine the allelic specificity of peptide presentation.

Down-regulation of murine contact sensitivity by hapten-amino acid derivatives

The low responsiveness of contact sensitivity (CS) in sensitized and challenged mice was induced by using hapten-amino acid derivatives. Subcutaneous injection of trinitrophenyl (TNP)-lysine or oxazolone-glycine inhibited ear swelling responses in mice that received rechallenge. The inhibitory effect was long-lasting and antigen-specific. TNP-lysine blocked the transfer of CS in vivo and the binding of immune lymph node cells to antigen in vitro. Thus, the suppression was mediated by inhibition of effector cells, but not associated with the generation of efferent limb-acting suppressor cells. The tool reported herein seems to be quite useful for controlling ongoing murine CS to simple chemicals.

Conjunctival mast cells and the allergic late phase reaction

An active model of ocular anaphylaxis was developed in guinea pigs to evaluate the histopathology of the early (EPR) and late (LPR) phase reaction, focusing on the role of mast cells. Five groups (n = 6) of animals were actively immunized by first injecting into each of the axillary and inguinal lymph node areas, 0.25 ml of an emulsion containing 1 mg dinitrophenyl bovine gamma-globulin (DNP-BCG) with 0.5 ml complete Freund's adjuvant. After two weeks, an intramuscular injection of 0.5 ml of an emulsion containing 1 mg DNP-BGG with 0.5 ml of incomplete adjuvant was administered. One month after the first injection, animals were sacrificed after topical ocular challenge with 10 microliters of 1 mg/ml divalent hapten, di-DNP-lysine, in one eye and phosphate buffered saline (PBS) in the fellow eye as control. Clinical reactions were graded over time and histology evaluated at the endpoint (time 0, 0.5, 3, 9, and 24 h). Results showed that all animals clearly developed both an EPR and an LPR, as either a biphasic, multiphasic or prolonged clinical response. A small percentage of mast cells were degranulated at baseline, whereas, at 0.5 h, 95% of mast cells were degranulated in the eyes treated with specific hapten and 25% in the control eyes treated with PBS. At 3 h, 84% of the mast cells were degranulated. This value rose to 89% at 9 h, and remained unchanged at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for antibodies associated with halothane hepatitis

The diagnosis of halothane hepatitis (HH) may be assisted by detection of antibodies reacting to trifluoroacetylated proteins (anti-TFA antibodies). An enzyme-linked immunosorbent assay (ELISA) utilizing trifluoroacetylated rabbit serum albumin (TFA-RSA) as antigen detected anti-TFA antibodies in 67% of sera from patients for whom a clinical diagnosis of HH was made. Anti-TFA antibodies were detected in 33% of sera when using an ELISA with liver microsomal protein from halothane-treated rabbits as antigen. Absorption of the sera with untreated rabbit liver microsomal protein before using the microsomal protein ELISA resulted in detection of anti-TFA antibodies in 42% of sera. Using the presumptive hapten N-epsilon-trifluoroacetyl-1-lysine to block antibody binding in an ELISA resulted in positive detection in 50% of sera: the results did not always agree with the other ELISA methods. The TFA-RSA ELISA was the most sensitive method and, combined with the TFA-lysine blocking ELISA, resulted in 92% of sera from HH patients testing positive for HH-associated antibodies.

Characterization of antibodies to advanced glycosylation end products on protein

Antibodies directed against advanced glycosylation end products (AGEs) formed during a Maillard reaction have been generated and characterized. Since protein-bound AGEs recognized by the antibodies were labile to acid hydrolysis, the antibodies were further characterized by using the AGE-alpha-acetyl-L-lysine methyl ester (AGE-ALME) with a brown and fluorescent property as well as the AGE-proteins. The antibodies reacted with fluorescent compounds, rather than brown pigment compounds, in the AGE-ALME. The fluorescent compounds in the AGE-ALME were separated into four fluorescent compounds by reversed-phase thin layer chromatography (TLC). Of the fluorescent compounds tested, compound 3 (Rf = 0.63), as designated on a TLC plate, showed the highest affinity for the antibodies. In addition, the antibody recognition to the cross-linked oligomers with fluorescence in the AGE-protein was investigated by using bovine pancreatic ribonuclease A (RNase), which is known as a model protein for studying AGE-induced cross-linking. Fluorescence in the AGE-RNase existed in both of the oligomers and the monomer. The cross-linked oligomers exhibited higher affinity to the antibodies than did the monomer, which has a similar degree of fluorescent intensity. These results indicate that our antibodies against cross-linked protein-bound AGEs may serve as a useful tool to elucidate pathophysiological roles of advanced Maillard reaction in diabetic complications and aging processes.

The influence of epitope density on the estimation of the affinity of antibody for complex antigens

The influence of the epitope density of the antigen on antibody affinity values determined by fluid- and solid-phase immunoassays was assessed. The affinity of the interaction of a panel of monoclonal anti-DNP antibodies of different affinities (as determined by equilibrium dialysis) for DNP-protein conjugates of various hapten substitution ratios was used as the test system. The results obtained showed that the epitope density of the antigen markedly influences the observed affinity values obtained by both experimental approaches. However, the monoclonal antibodies were ranked in affinity terms by both assays in a similar order to that given by equilibrium dialysis. It is concluded that provided due care is exercised in choosing an appropriate epitope density for the test antigen, these methods can be used to provide rapid estimations of average antibody affinities.

Double hapten challenge in guinea pigs undergoing an ocular late-phase reaction

Clinical and histological profiles of guinea pig conjunctiva undergoing late-phase reaction (LPR) were evaluated before and after additional antigenic challenge. Four groups of animals were passively sensitized with IgG1 antibodies, challenged with the specific hapten di-DNP-lysine, and rechallenged during LPR either with di-DNP-lysine, or with PBS, or with an aspecific antigen to characterize the reactivity of the inflamed conjunctival tissues. The course of the clinical anaphylactic responses was modified slightly only by challenge with a specific hapten during LPR. However, no significant changes in the inflammatory cell profile were observed in conjunctiva undergoing LPR after an additional challenge. This suggests the participation of mechanisms which may mediate the attenuation of the anaphylactic response in physiologic conditions of persistent antigen provocation.

A continuous flow immunoassay for rapid and sensitive detection of small molecules

An immunosensor operating in continuous flow and capable of detecting low molecular weight antigens is described. The approach differs from previously described continuous flow assays by not requiring incubation steps or the introduction of additional reagents following the loading of the sample into the system. Detection of the antigen is rapid, occurring within 3 min in the system described. The assay is based on the binding of labeled antigen to an immobilized antibody, with subsequent displacement of the labeled antigen when antigen is present in the buffer flow. Signal detection occurs downstream of the antigen recognition event. In this study, the hapten 2,4-dinitrophenol (DNP) as DNP-lysine was used as model antigen. To generate a labeled antigen, DNP was coupled to the terminal amino group of insulin A chain (tetra S-sulfonate form) which provides two tyrosine residues for the introduction of an 125I-label (DNP-Ins-125I) or three carboxyl groups for the attachment of three fluorescein residues (DNP-Ins-Fl). The radiolabeled antigen was used to establish assay conditions. Subsequently, fluorescein was substituted for the radioisotope label in order to develop an assay independent of the restrictions associated with isotopes. Using this flow immunoassay, we were able to detect DNP-lysine down to a detection limit of 143 nM (29 pmol/200 microliters) using DNP-Ins-125I or DNP-Ins-Fl as labeled antigen. The density of immobilized antibody and the flow rate were identified to be critical parameters for the sensitivity of the assay.

Early and late phases of ocular anaphylaxis in actively immunized guinea pigs

A model of ocular anaphylaxis with distinct early- and late-phase components was studied in actively immunized guinea pigs. Twenty guinea pigs were injected with dinitrophenylated (DNP) bovine gamma globulin emulsified in Freund's complete adjuvant and challenged topically with di-DNP-lysine. Clinical signs were monitored over a 48 h period. An early-phase reaction (EPR) characterized by conjunctival edema, conjunctival erythema, lid swelling, and lid redness was observed. This reaction peaked at 0.5 h after challenge and subsided to a low point at 3-4 h. Subsequently, a second episode of lid swelling and lid redness was observed at 4-8 h. All animals in both groups exhibited an EPR. In addition, 75% of the animals underwent an EPR and an LPR. No animals exhibited an isolated LPR. Of the animals that underwent a dual response, 47% were biphasic, 6% were prolonged and 47% were multiphasic. The development of an active model of ocular anaphylaxis exhibiting both EPR and LPR components will enable studies of mechanisms which regulate the frequency and magnitude of these ocular allergic responses.

An in vitro method for predicting sensitizing properties of inhaled chemicals

A method for monitoring chemical reactivity in aqueous solutions, at neutral pH and 37 degrees C, was developed. The chemical was allowed to react with a lysine-containing peptide, and the reaction was monitored with high-performance liquid chromatography. Simple acids, bases, and solvents did not react with the peptide, whereas isocyanates, anhydrides, and chloramine-T, substances well known for their sensitizing and asthma inducing properties, did. Thus a positive test strongly suggested that the chemical had the potential to act as a hapten and cause sensitization when inhaled. Prepolymers of diphenylmethane diisocyanate were considerably more reactive than prepolymers of toluene diisocyanate or hexamethylene diisocyanate. Isocyanates blocked with caprolactam, butanone oxime, malonic acid diethylester, or isononyl phenol showed no reactivity. This result suggested a significantly reduced risk of respiratory reactions when such blocked isocyanates are handled at room temperature. One blocked isocyanate showed, however, considerable reactivity.

Antibodies against a peptide of cholera toxin differing in cross-reactivity with the toxin differ in their specific interactions with the peptide as observed by 1H NMR spectroscopy

The interactions between the aromatic residues of the monoclonal antibody TE34, and its peptide antigen CTP3, have been studied by 2D TRNOE difference spectroscopy. The sequence of CTP3 corresponds to residues 50-64 of the B subunit of cholera toxin (VEVPGSQHIDSQKKA). Unlike two previously studied anti-CTP3 antibodies (TE32 and TE33), the TE34 antibody does not bind the toxin. The off-rate of CTP3 from TE34 was found to be too slow to measure strong TRNOE cross-peaks between the antibody and the peptide. Much faster off-rates, resulting in a strong TRNOE, were obtained for two peptide analogues: (a) CTP3 with an amide in the C-terminus (VEVPGSQHIDSQKKA-NH2) and (b) a truncated version of the peptide (N-acetyl-IDSQKKA). These modifications do not interfere significantly either with the interactions of the unmodified part of the peptide with the antibody or with intramolecular interactions occurring in the epitope recognized by the antibody. The combined use of these peptides allows us to study the interactions between the antibody and the whole peptide. Two tyrosine residues and one or more tryptophan and phenylalanine residues have been found to interact with histidine-8, isoleucine-9, aspartate-10, lysine-13 and/or lysine-14, and alanine-15 of the peptide. In the bound peptide, we observe interactions of a lysine residue with aspartate-10 beta protons. While the peptide epitope recognized by TE34 is between histidine-8 and the negatively charged C-terminus, that recognized by TE32 and TE33 is between residues 3 and 10 of the peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of topical dexamethasone on the ocular allergic reaction in passively sensitized guinea pigs

We examined the effect of extended topical pretreatment with dexamethasone (Dex) on the ocular allergic response in passively sensitized guinea pigs. The passive IgG1 antibody dependent guinea pig model used in these studies demonstrates both early- and late-phase ocular anaphylactic reactions. Fourteen hours prior to challenge with the hapten di-DNP-lysine, three groups of guinea pigs were sensitized subconjunctivally with antiserum rich in IgG1 anti-DNP antibodies in both eyes (group 1, n = 11) or in one eye (group 2, n = 9; group 3, n = 10). The contralateral eyes of animals in groups 2 and 3 received normal guinea pig serum. At 1-hour intervals, beginning 6 h prior to challenge, guinea pigs in group 1 received 0.1% Dex in 0.5% hydroxymethylcellulose (MC) topically in one eye and 0.5% MC in their other eye. Animals in group 2 were treated on the same schedule with 0.5% MC only in both eyes. Animals in group 3 were not pretreated. Conjunctival edema, conjunctival erythema, periorbital swelling, and lid erythema were scored independently in the upper and lower lids of both eyes of all animals for 10 h. Comparisons between the scores of Dex-pretreated eyes in group 1 and MC-pretreated eyes in group 2 or untreated eyes in group 3 revealed no significant differences in any clinical sign at 0.5 h (early-phase reaction). However, these comparisons demonstrated significant reductions in all four clinical signs in animals of groups 1 from 1 to 8 h and marked reduction or complete absence of signs from 6 to 10 h (late-phase reaction).(ABSTRACT TRUNCATED AT 250 WORDS)

Histology of ocular late-phase reaction in guinea pigs passively sensitized with IgG1 antibodies

The ocular late-phase reaction (LPR) is a mast cell-dependent, delayed inflammatory reaction developing 4-12 h after the early-phase reaction (EPR). We developed a passive IgG1 antibody-dependent guinea pig model that clinically reproduced the biphasic reaction of ocular EPR and LPR. An EPR was observed in all animals; a biphasic, multiphasic or prolonged inflammation was observed in the animals maintained for 9 and 24 h. The substantia propria of eyes undergoing EPR (0.5 h) showed intense edema, mast cell degranulation (88%), and 4-fold increase in eosinophils. At 9 h, the neutrophils and eosinophils had increased 11- and 25-fold, respectively. The number of basophils and lymphocytes was significantly increased compared to the controls (p less than 0.05). Of the mast cells, 45% were degranulated compared with 19% for controls. Cellular reactions had subsided by 24 h. Conjunctival epithelium also accumulated inflammatory cells as did the stroma of the lid skin. These histologic changes in ocular tissues undergoing anaphylaxis demonstrated that mast cell degranulation was most severe in the early phase, whereas neutrophil, eosinophil, and basophil accumulation was most marked in the late phase.

Divalent hapten-induced intestinal anaphylaxis in the mouse: uptake and characterization of a bystander protein

We examined the mucosal barrier function during anaphylaxis induced by the hapten N,N'-di-2,4,dinitrophenyl-lysine (di-DNP-lysine) in BDF1 female mice immunized with dinitrophenylated Ascaris suum extract. Immunized mice were gavaged with 10 mg or 50 mg of ovalbumin (OVA) with or without N,N'-di-2,4,-DNP-lysine (di-DNP-lysine). Animals that received di-DNP-lysine underwent anaphylaxis and were observed to have significantly greater serum concentrations of immunoreactive OVA (iOVA) than control mice. The severity of anaphylaxis, which varied with the dose of di-DNP-lysine administered, influenced the uptake of OVA; greater amounts of iOVA were detected in serum of mice undergoing more severe anaphylaxis. On gel permeation of serum from both groups of mice, immunoreactive OVA was found to have a molecular size similar to native OVA. Di-DNP-lysine is a synthetic hapten that reliably induced anaphylaxis in sensitized animals challenged by gavage. Anaphylaxis resulted in the uptake into the circulation of greater quantities of an unrelated protein antigen present in the intestinal lumen. The protein antigen that was taken up into the circulation appeared to be intact and thus may have an influence on the development of the immune response, or lack thereof, to this bystander antigen.

Immunochemical reactivity of native and modified preparations of pig kidney diamine oxidase

This paper describes the antigenicity of pig kidney diamine oxidase [EC 1.4.3.6] and the possible role of constituent amino acids in the epitope structure of the enzyme. The loss of 62% of the biological activity after DAO-anti-DAO antibodies interaction was attributed to the steric hindrance caused by binding of antibody to the enzyme molecule. A gradual loss in antigenicity during ultraviolet (UV) irradiation was observed without any significant conformational change, demonstrating the destruction of antigenic determinants. However, ethoxyformylation of nine histidyl residues with complete inactivation caused no change in immunoreactivity. The results indicate that the antigenic sites and catalytic sites are located at different positions along the polypeptide chain. Moreover, the results of lysine residue modification were suggestive of possible involvement of lysine in the antigenic determinants of DAO.

A "minimal epitope" anti-protein antibody that recognises a single modified amino acid

Antibodies that recognise proteins bind to epitopes of varying size, but a grouping of the order of six amino acids, contiguous or not, is regarded as a typical number. By using as immunogen a highly abundant and universal eukaryotic nuclear protein (histone H4) modified in a manner not typical of secreted proteins (acetylation of lysine side chains), antiserum has been raised in rabbits having the single amino acid epsilon-N-acetyl lysine as the recognition epitope. The affinity-purified antibody should be useful for studying the functional role of this modification. The methodology has potential for raising antibodies to other types of post-translationally modified proteins.

A method for localizing the early products of nonenzymatic glycosylation in fixed tissue

The process of nonenzymatic glycosylation (NEG) may play a significant role in the development of chronic complications of diabetes. Early products of NEG can be measured by various biochemical methods. A method has been developed to localize these early products of glycosylation in vivo in fixed tissue sections of normal and diabetic skin using monoclonal antibodies specific for glucitollysine, which is formed when the early products of NEG are chemically reduced in vitro. Carnoy's-fixed, paraffin-embedded skin samples from six diabetic and 13 nondiabetic subjects were sectioned, mounted on glass slides, and reduced for one h in 100 mM NaBH4. Immunolocalization was by the avidin--biotin immunoperoxidase method. Diabetic skin consistently stained more intensely for glucitollysine than nondiabetic skin. Staining around vessels, in particular, and of the collagenous matrix in general, was markedly enhanced in diabetic skin compared with nondiabetic skin. Antigens present in both the epidermis and the eccrine structures reacted with the antibody in both diabetic and nondiabetic skin but with greater intensity in the diabetic skin. This study has shown that it is possible to localize the early products of NEG in tissue sections using monoclonal antibodies. The findings correlate with biochemical data that show increased NEG in diabetics compared with nondiabetics. This technique should prove valuable for further investigations of the role of NEG in the pathogenesis of diabetes.

Attenuation of rat conjunctival response by repeated hapten applications

Attenuation of the rat conjunctival response by repeated topical challenge with dinitrophenyl (DNP) hapten was demonstrated in our study. Adult rats were immunized by intraperitoneal injections of dinitrophenylated Ascaris suum extract (DNP-Asc) and alum. Serum levels of anti-DNP homocytotropic antibody were determined by passive cutaneous anaphylaxis in rats prepared with antibody 48 hours earlier. In other animals, topical challenge was performed by applying N,N'-di-2,4-DNP-L-lysine (di-DNP-lysine) in phosphate-buffered saline (PBS) to one eye; PBS alone was applied to the fellow eye. The degree of conjunctival reaction was assessed clinically, and ocular tissues were processed for histological evaluation. The intensity of the conjunctival reaction and extent of mast cell degranulation were significantly greater after one challenge with di-DNP-lysine than after multiple challenges. In the multiple-challenge group, the contralateral eye remained responsive to a single challenge with di-DNP-lysine. These results may have implications for therapeutic interventions in ocular anaphylaxis.

Radioimmunoassay of glycosylated albumin with monoclonal antibody to glucitol-lysine

An immunoassay specific for glycosylated albumin was developed by the use of beads coated with antibody to human serum albumin (beads) and 125I-labelled monoclonal antibody to reduced bovine glucosylated low density lipoprotein. One bead was capable of binding 100 ng of serum albumin which had been treated with sodium borohydride (NaBH4) to reduce the Schiff base in the protein. The monoclonal antibody reaction with glucitol-lysine epitopes on the reduced glucosylated proteins and amino acids studied, including human serum albumin (HSA), bovine serum albumin and hippuryl-L-lysine. The detection limit of this assay was 100 pmol/mg HSA, which was sensitive enough for clinical use. The mean serum reduced glycosylated albumin concentration measured by this new method was significantly higher in diabetic patients (2.63 +/- 0.35 nmol/mg HSA, n = 32) than in healthy subjects (0.53 +/- 0.05 nmol/mg HSA, n = 38). The serum reduced glycosylated albumin concentration correlated with both hemoglobin A1c (r = 0.69, p less than 0.005) and the fasting blood glucose level (r = 0.51, p less than 0.005) in diabetic patients.

A novel enzyme immunoassay of anti-insulin IgG in guinea pig serum

A novel enzyme immunoassay of anti-insulin IgG in guinea pig serum is described. Guinea pig anti-insulin serum diluted with nonspecific guinea pig serum was incubated with dinitrophenyl biotinyl nonspecific rabbit IgG-insulin conjugate and a rabbit (anti-dinitrophenyl bovine serum albumin) IgG-coated polystyrene ball. After washing to eliminate nonspecific guinea pig IgG in the diluted serum, the polystyrene ball was incubated with dinitrophenyl-L-lysine to elute the complex of anti-insulin IgG and the conjugate. The eluate was incubated with an avidin-coated polystyrene ball. Finally, the amount of guinea pig anti-insulin IgG in the complex trapped onto the avidin-coated polystyrene ball was measured by incubation with rabbit (anti-guinea pig IgG) Fab'-peroxidase conjugate. This enzyme immunoassay was 10,000-fold more sensitive than the conventional enzyme immunoassay using insulin-coated polystyrene ball and rabbit (anti-guinea pig IgG) Fab'-peroxidase conjugate.

Quantitative enzyme-linked immunosorbent assay (ELISA) for non-enzymatically glycated serum protein

A competitive ELISA for quantitative determination of glucitollysine, the reduced hexose alcohol form of glucose conjugated to the epsilon amino group of lysine was developed. We applied it to measure non-enzymatically glycated serum proteins. The antiserum obtained by immunizing guinea pigs with reductively glycated human albumin was capable of identifying and quantitating glucitollysine residues of serum proteins in normal and diabetic subjects after reduction of the proteins with sodium borohydride. The ELISA assay developed here had satisfactory reproducibility as judged by the intra-assay precision of 2.3-7.6% and the interassay precision of 6.7-9.8%. Results from this assay procedure correlated well with those from the radioimmunoassay and the boronate affinity chromatography procedure. The data suggested that diabetic serum proteins contained at least three times as much immunochemically detectable glucitollysine residues as normal serum proteins after reduction of the proteins with sodium borohydride. This method allows to quantitate glucitollysine residues on any of the proteins that have been implicated in the pathological sequelae of diabetes.

Human immune responses in vivo to protein (KLH) and polysaccharide (DNP-Ficoll) neoantigens: normal subjects compared with bone marrow transplant patients on cyclosporine

Thymus-independent (TI) and thymus-dependent (TD) primary immune responses were measured in 67 controls and 13 bone marrow transplant (BMT) recipients treated with cyclosporine (CSP) by immunizing with a synthetic antigen (DNP-Ficoll) and keyhole limpet haemocyanin (KLH). DNP-Ficoll induced similar TI antibody responses in controls and BMT recipients except that antibody levels declined much more rapidly in BMT recipients. The IgM and IgG antibodies induced by DNP-Ficoll only recognized the DNP epitope and not the Ficoll carrier. Both IgM and IgG classes of antibody showed similar TI behaviour upon immunization and re-immunization. The antibodies to DNP-Ficoll were overwhelmingly of the IgG1 subclass. The TD response to KLH evoked both delayed hypersensitivity (DH) and antibody production. DH developed at the site of immunization in 68% of controls and in 88% upon subsequent challenge with KLH. None of the BMT recipients on CSP developed DH. KLH antibody arose in 88% of controls but in only one BMT recipient on CSP. Eight BMT recipients were re-immunized with KLH 2-6 weeks after stopping CSP and only one made primary DH and antibody responses, arguing that CSP inhibited priming as well as any detectable response to KLH. The immunization procedure described has proved a sensitive and comprehensive method of quantitating human immune responses in vivo and is readily adaptable for in vitro studies.

Antibodies to nonenzymatically glucosylated albumin in the human serum

The existence of antibodies to nonenzymatically glucosylated albumin was investigated in nondiabetic and diabetic subjects. The sera from both the nondiabetic and the diabetic subjects were shown to contain the proteins which bound to reductively glucosylated albumin. An enzyme-linked immunosorbent assay demonstrated that the antibodies specific for reductively glucosylated albumin existed in the sera containing the binding proteins. For binding the antibodies glucitollysine as the glucose adduct in reductively glucosylated albumin was an effective competitor. The hexose alcohol epimers glucitol and mannitol were also effective competitors compatible with glucitollysine. Our results suggest that the antibodies to reductively glucosylated albumin are widely present not only in the diabetic subjects but also in the nondiabetic subjects and cross-react with the hexose alcohol.