Kd Components Research Articles

Higher antigen occupancy of high avidity CSP serum antibodies associates with protection against human malaria.

R21, a next generation malaria vaccine candidate, demonstrated 74-77% efficacy among children living in a malaria endemic area. In a phase IIa controlled human malaria infection (CHMI) study, R21 demonstrated 48.6% to 78.2% vaccine efficacy. The immune mechanisms responsible for protection by the R21 immunogen are unknown. We hypothesized that both magnitude and avidity of R21-induced polyclonal antibodies (pAbs) contribute to protection status. The biophysical properties of plasmodium falciparum (Pf) circumsporozoite protein (CSP) specific pAbs of participants from CHMI study were measured by Biolayer Interferometry, including antigen binding response and dissociation rate constant (kd) when binding to recombinant CSP, central repeat-peptides (NANP)6 and (NPNA)3, and the virus like particle R21 vaccine immunogen presenting 19 repeats of NANP motif, with the C-terminal region of CSP fused to the hepatitis B surface antigen. An innovative polyclonal antibodies avidity resolution tool (PAART) was used to derive kd values reflecting different avidities of pAbs and the fraction of their contribution to total binding (antigen occupancy). We found that protected vaccinees from all groups combined displayed higher median binding response (p<0.05 for R21, CSP and (NPNA)3, Mann-Whitney U test) and slower median kd values (p<0.01 for (NANP)6 and (NPNA)3, Mann-Whitney U test) compared to non-protected vaccinees. For the majority of participants, further dissecting the heterogeneity of avidities of the R21 immunogen-induced antibodies revealed two kd components, 10−4 s−1 (higher avidity component) and >10−2 s−1 (lower avidity component). Interestingly, the median antigen occupancy of higher avidity component for CSP, (NANP)6 and (NPNA)3 binding, i.e., the dominant fraction (82-99% occupancy, mean value 95%), was greater in the protected than non-protected vaccinees. These results suggest that high magnitude and avidity pAbs contribute to the R21 vaccine protection against Pf sporozoite infection.

Abstract 3021: Understanding the effects of a ketogenic diet against pancreatic cancer

Abstract With an overall survival of less than 3%, pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer-related death in the U.S. at its advanced stages. With the most promising therapeutics, the overall survival after a stage IV PDAC diagnosis is only at 11.1 months. The marginal effects of current therapeutics emphasize the importance of developing new approaches to treat PDAC. In a wide range of cancer subtypes, a ketogenic diet has shown encouraging effects as combination therapy. However, the underlying anti-tumorigenic pathways involved in this diet alone are still not well understood. The ketogenic diet’s core elements and direct physiologic effects (ketone bodies, fatty acids, low glucose, low insulin levels) potentially alter PDAC biology that span from redox homeostasis to mitochondrial metabolism, and epigenetic modifications. We hypothesized that in carefully controlled in vitro and in vivo experiments, KD components delay growth of PDAC. Additionally, we hypothesize that understanding the underlying drivers of the anti-tumor effects of a ketogenic diet could be leveraged into the rational design of combination therapies that augment these anti-tumor effects. We show that in the subcutaneous mouse model of PDAC, tumor growth is markedly delayed under ketogenic diet restrictions Furthermore, in PDAC cell culture models, we observed anti-cancer effects when the ketogenic diet core elements are isolated. Specifically, fatty acids and ketone bodies inhibit PDAC cell growth, particularly under high glucose conditions. These effects are somewhat attenuated under low glucose, suggesting that these elements result in competing effects on PDAC cells (i.e., support some pro-survival pathways while inhibiting others). Future studies seek to better delineate the mechanistic impact of the principal ketogenic diet elements on metabolic pathways with a focus on mitochondrial metabolism, as well effects on epigenetic signaling. Citation Format: Omid Hajihassani, Ali Vaziri-Gohar, Mehrdad Zarei, Jonathan Hue, Helen Cheng, Anusha Mudigonda, Erryk Katayama, Hallie Graor, Jordan Winter. Understanding the effects of a ketogenic diet against pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3021.

Dynamics of strong and radiative decays of Ds-mesons in the hadrogenesis conjecture

The positive parity scalar D*s0(2317) and axial-vector D*s1(2460) charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D(Ds)-meson ground states. The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg–Tomozawa interaction in the chiral Lagrangian. Chiral corrections to order Q2χ are calculated and found to be small. The D*s0(2317) and D*s1(2460) mesons decay either strongly into the isospin-violating π0Ds and π0D*s channels or electromagnetically. We show that the π0-η and (K0D+-K+D0) mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the KD component of the states. The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q2χ. We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays. The radiative width are sensitive to both ηDs and KD components, hence providing information complementary to the strong widths on the positive parity Ds-meson structure.

Physico-Chemical and Functional Properties of Proteins from Pelagic Fatty Fish (Sardinella longiceps) as a Function of Water Washing

The minced meat from oil sardine (Sardinella longiceps) was subjected to once, thrice, and five water washings. The changes in proximate composition of meat, physico-chemical and functional properties of proteins as affected by number of washings were investigated. A positive correlation (p < 0.05) existed between number of washings and fat content, water absorption capacity, gel strength, expressible water content and emulsion capacity of meat. A reduction in low molecular weight components of proteins during different washings was evident from gel filtration profile. The sodium dodecyl sulfate polyacrylamide gel electrophoresis patterns of total proteins revealed that increase in myosin heavy chain content and decrease in the concentration of 55 and 36 kD components with number of washings. The dynamic visco-elastic behavior of once washed sardine meat in the temperature range of 30–90°C had higher ability to form elastic component (G′) than thrice and five times washed meat.

Lack of Suppressive Antibody Activity in Sera from Patients with Active-Phase Autoimmune Diseases

To investigate the presence of a suppressive antibody activity in sera from patients with autoimmune diseases, the IgG autoreactivity in whole serum was compared to that of the IgG fraction purified by affinity chromatography on protein G-sepharose. Competitive inhibition assays on the binding to histone, dsDNA, RNP and thyroglobulin of the purified IgG fraction by the autologous IgM present in serum without IgG and depleted of < 100 kD components (named IgM fraction) were also performed. The IgG reactivity to the autoantigens tested was considerably increased in the IgG fraction than in the whole serum drawn from a healthy control and from three SLE patients in an inactive-phase of disease. Addition of the IgM fraction to the autologous purified IgG resulted in a dose-dependent inhibition of IgG binding to the autoantigens tested. However, no differences were observed between the autoreactivity of the IgG in whole serum and that of the purified IgG fraction from active-phase SLE patients, or from two patients with autoimmune thyroiditis, and the autologous IgM fractions did not inhibit significantly binding to the autoantigens under study of the purified IgG fraction. Our findings support the concept that the IgG autoreactivity in physiological conditions is regulated by idiotypic interactions between IgG and IgM, and suggest that this regulation is broken in the active phase of autoimmune diseases and that clinical remission from SLE could be associated with the restoration of this control mechanism. Additionally, qualitative differences, such as polyreactivity or change of idiotype in the autoreactive IgG fraction from active-phase disease might contribute to escape of regulation.

Royal jelly–induced asthma and anaphylaxis: Clinical characteristics and immunologic correlations

temperature difference could be perceived either directly by elevated blood temperature affecting cells in the hypothalamic preoptic area, or indirectly by blood temperature first affecting peripheral neuronal receptors, which in turn stimulate the preoptic area. It would have been tempting to assume that direct heating of the blood could bypass peripheral neuronal receptors. However, because sequential skin temperatures were not recorded along with oral temperatures, this assumption cannot be established. Nevertheless, this case is a unique example of the temperature difference needed to be perceived by the central temperature regulation system in order to provoke the common efferent reflex leading to hives in CU.

INHIBITING THE ACTIVITY OF ACTINIDIN BY ORYZACYSTATIN FOR THE APPLICATION OF FRESH KIWIFRUIT TO GELATIN-BASED FOODS

Fresh kiwifruit has potent proteinase activity that can be ascribed to actinidin, a cysteine proteinase. Without regulating this activity, kiwifruit can not be used satisfactorily as a food ingredient for protein-based foods. We found that oryzacystatin, a rice seed cysteine proteinase inhibitor, stoichiometrically inhibits the actinidin activity and can be used in making gelatin jellies with fresh kiwifruit slices. We also found that a gelatin solution mixed with an actinidin preparation did not form a gel because 118 kd and 130 kd components in the gelatin had undergone degradation. However, gelation occurred with no appreciable degradation in these two major gelatin components when oryzacystatin was added to this actinidin preparation.

Multiple neurotrophic factors including NGF-like activity in nerve regeneration chamber fluids

Silicone nerve regeneration chambers were implanted between the cut ends of the sciatic nerve of adult rats. Neurotrophic activities in cell-free fluids collected from the chambers were determined using bioassays for survival of embryonic chick ciliary and sympathetic neurons in culture. Separation by molecular exclusion HPLC of the components of fluids collected l, 2 or 3 days after implantation revealed the presence of a multitude of neurotrophic factors differing in their molecular weights, specificity towards the two types of neurons, and time course. Antiserum to nerve growth factor partially blocked sympathetic activity of fluids collected at 1 day. Affinity purified antibody was also effective and completely eliminated bioactivity of HPLC fractions corresponding to the molecular weight of nerve growth factor. The presence in the fluids of 13–18 and 20–32 kD components active towards ciliary neurons is consistent with the release of fibroblast growth factor and ciliary neurotrophic factor respectively. The stimulation of sympathetic neurons by the 13–18 kD material, and also by 4–6 and 7–11 kD components cannot be entirely accounted for by known factors. This study demonstrates that a number of neurotrophic factors, which differ in their specificity towards sympathetic and parasympathetic neurons, are made available to the region of axonal regrowth over the first few days of regeneration. Contrary to earlier reports, nerve growth factor-like activity was shown to be present in nerve regeneration chambers.

The target antigen of anti-tubular basement membrane antibody-mediated interstitial nephritis.

Our previous studies showed that 54 kD and 48 kD tubular basement membrane (TBM) proteins were the major form of the target antigen involved in anti-TBM antibody-mediated tubulo-interstitial nephritis in humans. In those studies, we isolated the 54 kD glycoprotein (named gp54) from collagenase-digested bovine TBM. NH2-terminal amino acid sequencing indicated that gp54 represented a newly defined glycoprotein. In this study, we further characterized the target antigen, using mouse monoclonal antibodies to gp54 and polyclonal anti-gp54 peptide antibody. Two monoclonal antibodies (H79 and H80) were established, and they reacted, by immunofluorescence, predominantly with the proximal TBM of humans, rabbits, and Wistar, Sprague-Dawley, and Brown-Norway rats, but not with that of Lewis rats. They were also fixed by blotting intensely to the 54 kD component and weakly to the 48 kD component of collagenase-digested human TBM. In vivo transfer of H79 to Wistar rats showed extensive linear binding of mouse IgG to the TBM and the basal membrane of the small intestine; however, no pathologic changes were seen by light microscopy. The anti-gp54 peptide antibody reacted with both the 54 kD and 48 kD TBM components of human TBM. mRNA was prepared from rabbit kidneys, and fractionated to enrich mRNA encoding the 54 kD and 48 kD peptides. On in vitro translation experiments with the mRNA fraction, the 54 kD and 48 kD peptides were immunoprecipitated with anti-gp54 antibodies. These findings indicate that the 54 kD and 48 kD components are encoded with different mRNA, but that they share the same antigenic epitope.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and characterization of a 30 kd major allergen from Parapenaeus fissurus

The allergenic components of the shrimp ( Parapenaeus fissurus) were identified by immunoblotting, with sera from 10 allergic patients. Six components, ranging in molecular weight from about 86 to 39 kd, showed IgE-binding activity and were identified as allergens of the shrimp. The component with a molecular weight of about 39 kd showed the highest frequency of IgE binding (70%) and was considered to be one of its major allergens. Two monoclonal antibodies against this 39 kd component were generated, and their antigenic cross-reactivity with five different kinds of seafood, shrimp, crab, cuttlefish, oyster, and pomfret was analyzed. Monoclonal antibody 1-6-10B reacted with the 39 kd component from shrimp only, but monoclonal antibody 2-7-IE also reacted with the 39 kd component from crab. By extraction with 0.5% sodium dodecylsulfate and ethanol precipitation, a highly purified shrimp 39 kd component was obtained. In two-dimensional gel electrophoresis six isoforms of this purified 39 kd component, with isoelectric point values from purified 39 kd component, with isoloelectric point values from 5.1 to 5.6, were identified. No marked difference was observed when the amino acid composition of this purified 39 kd allergen was compared with those of serum albumin from different animals. They all contain a high proportion of acidic amino acids. There was also a 62% to 83% sequence homology among three different pairs of peptide fragments of purified 39 kd components of shrimp and crab. In conclusion, a 39 kd major allergen from the shrimp has been identified and characterized in the present study. According to the suggestions of the International Union of Immunological Societies, this allergen is designated as Par f I.

Antibody to two forms of dihydrolipoamide acetyltransferase (PDC-E2) in primary biliary cirrhosis.

Dihydrolipoamide acetyltransferase, the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), is the major autoantigen in primary biliary cirrhosis. By immunoblotting with sera from patients with primary biliary cirrhosis, we observed a double band, of molecular weight 70 and 74 kD for PDC-E2, when a preparation of bovine heart mitochondria was not boiled prior to electrophoresis. This double band could also be detected using antisera raised in rats or rabbits against intact PDC or PDC-E2, but not in antisera raised against a synthetic decamer representing the lipoic acid binding sequence of PDC-E2; the latter reacted only with the 74 kD component. Antibody eluted from either the 70 or 74 kD component reacted with both 70 and 74 kD components. By ELISA, sera from patients with primary biliary cirrhosis reacted more strongly with a non-boiled than a boiled PDC-E2, whereas immune animal sera reacted equally with both preparations. Thus, according to whether preparations of PDC are boiled or not, two conformationally alternative forms of the PDC-E2 protein can be revealed by immunoblotting. The two forms in non-boiled preparations migrate at molecular weights corresponding to 70 and 74 kD.

Identification of jack‐jumper ant (Myrmecia pilosula) venom allergens

Jack-jumper ant venom proteins were electrophoretically separated on SDS-polyacrylamide gels, transferred to nitrocellulose and probed with sera from subjects who had experienced an allergic reaction after being bitten by a jack-jumper ant. Ant venom components that bound IgE antibodies were detected by addition of 125I-anti-human IgE followed by autoradiography. Of the 17 polypeptides resolved by electrophoresis only three, of molecular weights approximately 14 kD, 12 kD and 10 kD, bound IgE antibodies from the panel of 50 sera examined. There was a marked similarity in the binding patterns by individual sera with almost all of the sera recognizing the 14kD and 12 kD components. IgE-binding profiles of separated ant venoms from ants collected in different regions of Australia appeared to be very similar if not identical. Identification of the ant allergens is a necessary prelude to the preparation of standardized venom sac extracts suitable for safe and effective diagnostic and therapeutic use.

Identification and characterization of the major components of the Oncorhynchus mykiss Egg Chorion

The extracellular coat surrounding the fish egg, commonly called the chorion, is a primary envelope that confers biochemical and morphological identity typical of the species. Purified chorions can be easily isolated from either oocytes or ovulated eggs. The aim of this work was to analyze the macromolecular composition of the various chorion components in Oncorhynchus mykiss (Salmonids). SDS-PAGE analysis of purified chorion showed a reproducible pattern of four major components (129, 62, 54, and 47 kD), representing about 80% of total chorion proteins. The 129 and 47 kD polypeptides were periodic-acid Schiff (PAS) and concanavalin A positive. After chemical and enzymatic deglycosylation treatments only the 129 and 47 kD components proved to be glycosylated and to belong to the "asparagine-linked" glycoprotein family. Furthermore, peptide mapping performed on isolated polypeptides showed comigrating fragments on SDS-PAGE. These results suggest that the four main chorion polypeptides might share common structural features.

Desmoglein II-derived Glycopeptides in Human Epidermis

Antisera raised against a major 78 kD glycopeptide from pig epidermis were used to identify desmoglein II-derived glycopeptides in the conA-binding material isolated from human epidermis. In whole CaCl2-separated epidermis the antiserum recognized conA-binding components with apparent Mr of 115, 100, 82, 68, 50, 48, and 46 kD. The 82, 68, 48, and 46 kD immunoreactive bands were present in normal stratum corneum and plantar callus. Psoriatic scales contained significantly more of the 82 kD components and less of the 48 and 46 kD bands. Psoriatic scales also contained a major 50 kD conA-binding component unrelated to keratins or desmoglein II. Proteolytic peptide mapping showed that the major immunoreactive bands in normal stratum corneum and plantar callus were also chemically related. The 82 to 46 kD immunoreactive glycopeptides in plantar callus coincided with the major coomassie blue stained bands and were homogeneous on two-dimensional gels suggesting that this tissue may be a valuable source of human desmoglein II-derived glycopeptides. An antiserum directed against the electrophoretically co-purified 48/46 kD glycopeptides from plantar callus recognized the 82 to 46 kD bands in immunoblotting. In indirect immunofluorescence of frozen skin sections this antiserum stained the surface of epidermal cells in the spinous and granular layers of the tissue. In immunogold labeling of paraformaldehyde-fixed skin sections affinity-purified antibodies stained intact desmosomes in spinous and granular cells and desmosomal remnants in the stratum corneum. The results are consistent with our hypothesis that desmoglein II undergoes limited cleavage to stable fragments during terminal differentiation. Proteolytic degradation appears to be incomplete in psoriatic epidermis.

Factor V Is Activated and Cleaved by Platelet Calpain: Comparison With Thrombin Proteolysis

Abstract Platelets are known to process human factor V during secretion and/or membrane binding. We studied the functional and structural changes produced in human factor V by purified human platelet calpain (calcium- activated thiol protease) and compared the alterations with those induced by thrombin. A maximum increase in coagulant activity of 2.5- fold was observed when factor V (1 U/mL, 33 nmol/L) was incubated with calpain (0.03 U/mL, 2.7 nmol/L) in comparison with a 8.8-fold increment for alpha-thrombin (0.7 U/mL, 8 nmol/L) at 25 degrees C. Thrombin additions to reactions initiated by calpain resulted in further activation comparable to that of thrombin alone, whereas the subsequent addition of calpain had no effect on the extent or pattern of the activation of factor V by thrombin. The cleavage pattern of factor V produced by these two enzymes are distinctly different. Although thrombin activation eventually results in four final components designated C1 (150 kd), D (105 kd), E (71 kd), and F1F2 (71 to 74 kd), calpain yields initial components of 200 kd and 160 kd within one minute. Further digestion of the 200 kd species by calpain gives rise first to a polypeptide of 160 kd that is converted to a 140 kd and a 120 kd species by two minutes with an increase in coagulant activity. Immunoblotting of these fragments with the monoclonal antibody (MoAb) B10 directed to factor V and the thrombin-generated C1 fragment yields results demonstrating a common epitope in these calpain-generated components of 200, 160, 140 and 120 kd. The degradation of the initial 160 kd polypeptide gives rise to polypeptides of 100 and 65 kd, both undetectable on immunoblotting with MoAb B10. The 130, 87, 58, and 48 kd components are of less certain origin. Thus, platelet calpain generates a complex but reproducible cleavage pattern different from thrombin that may explain the partial activation observed. Nevertheless, calpain processing may play a role in early hemostatic reactions involving platelets before the appearance of the first thrombin molecule.

Factor V is activated and cleaved by platelet calpain: comparison with thrombin proteolysis

Platelets are known to process human factor V during secretion and/or membrane binding. We studied the functional and structural changes produced in human factor V by purified human platelet calpain (calcium-activated thiol protease) and compared the alterations with those induced by thrombin. A maximum increase in coagulant activity of 2.5-fold was observed when factor V (1 U/mL, 33 nmol/L) was incubated with calpain (0.03 U/mL, 2.7 nmol/L) in comparison with a 8.8-fold increment for alpha-thrombin (0.7 U/mL, 8 nmol/L) at 25 degrees C. Thrombin additions to reactions initiated by calpain resulted in further activation comparable to that of thrombin alone, whereas the subsequent addition of calpain had no effect on the extent or pattern of the activation of factor V by thrombin. The cleavage pattern of factor V produced by these two enzymes are distinctly different. Although thrombin activation eventually results in four final components designated C1 (150 kd), D (105 kd), E (71 kd), and F1F2 (71 to 74 kd), calpain yields initial components of 200 kd and 160 kd within one minute. Further digestion of the 200 kd species by calpain gives rise first to a polypeptide of 160 kd that is converted to a 140 kd and a 120 kd species by two minutes with an increase in coagulant activity. Immunoblotting of these fragments with the monoclonal antibody (MoAb) B10 directed to factor V and the thrombin-generated C1 fragment yields results demonstrating a common epitope in these calpain-generated components of 200, 160, 140 and 120 kd. The degradation of the initial 160 kd polypeptide gives rise to polypeptides of 100 and 65 kd, both undetectable on immunoblotting with MoAb B10. The 130, 87, 58, and 48 kd components are of less certain origin. Thus, platelet calpain generates a complex but reproducible cleavage pattern different from thrombin that may explain the partial activation observed. Nevertheless, calpain processing may play a role in early hemostatic reactions involving platelets before the appearance of the first thrombin molecule.

Autoantibody induced by experimental ocular Onchocerca infection: identification and characterization of autoantigens.

Hartley guinea pigs were injected with Onchocerca lienalis microfilariae (Mf) as a model for human infection with Onchocerca volvulus. Subconjunctival injection of guinea pigs with O. lienalis Mf results in penetration of Mf to the central cornea, and formation of acute inflammatory reactions resembling those of human onchocerciasis around dead Mf. Sera from these animals contain IgG autoantibodies directed against at least two components of 3M KC1 extracts of guinea pig cornea and liver. Components with apparent molecular weights of 94-99 and 110-120 kilodaltons (KD) were recognized in both cornea and liver extracts, while 100, 74 and 34 kD components were recognized in liver extracts only. Components of 140 kD and 84 kD were recognized in cornea extracts only. The guinea pig liver extract cross-reacted with homogenate antigens from O. lienalis Mf, while the guinea pig cornea extract did not. Autoantibody-mediated inflammatory mechanisms may contribute to immunopathologic processes in onchocerciasis.

Isolation of inhibin from ovine follicular fluid.

Two forms of inhibin with molecular weights of 65,000 and 30,000 (65 and 30 kD) were isolated from ovine follicular fluid using a combination of gel permeation chromatography, reversed-phase high-performance liquid chromatography and preparative polyacrylamide gel electrophoresis. The 65 kD form was partially purified approximately 315-fold whilst the 30 kD form was isolated as two isoforms (29 and 30 kD) of similar biological activity and in greater than 95% purity (1210-fold purification and 4.2% recoveries). On reduction the 30 kD form resolved into four components of 36, 31, 20-21 and 16 kD of which the 20-21 and 16 kD components were similar to the corresponding inhibin subunits isolated from porcine and bovine follicular fluid. The 36 kD component was established as a non-reducible inhibin-like material, based on its binding to antiserum raised against bovine 58 kD inhibin. The nature of the remaining non-reducible 31 kD component is unknown. Two NH2-terminal amino acid sequences (first 13 amino acids) identified in purified 30 kD inhibin were identical to the corresponding subunit amino acid sequences of bovine 31 kD inhibin.

ASSOCIATION OF ALKALINE PHOSPHATASE WITH AN AUTOANTIGEN RECOGNISED BY CIRCULATING ANTI-NEUTROPHIL ANTIBODIES IN SYSTEMIC VASCULITIS

A solid phase radioimmunoassay has been developed to detect circulating autoantibodies to neutrophil cytoplasmic antigens in systemic vasculitis. After fractionation of these antigens by size, with gel filtration high performance liquid chromatography, sera from patients with clinically different forms of systemic vasculitis, Wegener's granulomatosis (WG) and microscopic polyarteritis (MP), showed contrasting specificities of binding. WG sera bound to 100, 6·2, and 1·8 kD components, whereas MP sera bound only to the 100 kD component, allowing immunological distinction between the syndromes. The 100 kD component recognised by both WG and MP sera also showed alkaline phosphatase activity. Further evidence for this association was obtained by direct binding experiments between systemic vasculitis sera and calf-intestinal or human neutrophil alkaline phosphatase and by the cross-reactivity of W8, a monoclonal antibody raised to a neutrophil cytoplasmic autoantigen, with various preparations of the enzyme.

A labile antigen complex at the lymphocyte surface: the effect of the substratum on its expression.

Human T lymphocytes carry a surface antigen, detectable by a monoclonal antifibronectin antibody, which appears to consist of 150 and 55 kd components as revealed by SDS-PAGE. After in vitro culture of the lymphocytes on a plastic substratum for 48 hr comparatively few cells (40 +/- 18% in separate individuals) express the antigen. In contrast, the vast majority of lymphocytes cultured on a collagen matrix for the same time period maintains surface expression of the antigen (76 +/- 14% in separate individuals). Conditioned media from lymphocytes on plastic contain substantial amounts of antigenicity detectable by the same antibody, whereas conditioned media from lymphocytes on collagen are devoid of such antigenicity. The expression at the cell surface of other T lymphocyte antigens (Leu-4, Leu-3, and OKT8) is identical during culture on plastic and collagen for 48 hr. Collagen does not activate the cells to DNA synthesis or expression of IL 2 receptors, and consequently the potentiation of antigen expression by this substratum cannot be attributed to a mitogenic effect. The composition of subsets of T lymphocytes and the viability of the cells are the same on plastic and collagen, which excludes that the substratum-dependent variations in antigenicity reflect selection or loss of antigen-bearing cells. Thus, substratum-dependent regulation of the expression at the cell surface appears to be a unique property of the 150/55 kd T cell surface antigen. Culture on collagen substrata augments the number of lymphocytes showing motile behavior two to four times compared with culture on plastic.