Molecular mimicry between uveitopathogenic site of retinal S-antigen and Escherichia coli protein: induction of experimental autoimmune uveitis and lymphocyte cross-reaction

Experimental autoimmune uveitis (EAU) is caused by the immunization of microgram amounts of a soluble retinal protein, known as S-antigen, in susceptible animal strains including primates. The disease serves as an animal model of ocular inflammation. We induced EAU and pinealitis in Lewis rats with small synthetic peptides, corresponding to the amino acid sequence in Escherichia coli protein, which contains six consecutive amino acids identical to a uveitopathogenic site in human S-antigen (peptide M). EAU and pinealitis induced in rats by synthetic peptide derived from E. coli was indistinguishable from those induced by native S-antigen or other uveitopathogenic synthetic peptides corresponding to the amino acid sequence of S-antigen. Furthermore, lymph node cells from animals immunized with either peptide M or peptide derived from E. coli protein showed significant proliferation in the presence of either peptide when tested in vitro for lymphocyte mitogenesis using [3H]thymidine. Thus, molecular mimicry, a process by which an immune response directed against a nonself protein cross-reacts with a normal host protein, may play a role in autoimmunity.

Stimulatory effect of corticotropin-releasing neurohormone on human lymphocyte proliferation and interleukin-2 receptor expression

The supplementation of corticotropin-releasing factor (CRF) into the cultures of human blood lymphocytes caused increased proliferation both in the absence and presence of T cell mitogens such as concanavalin A and phytohemagglutinin. The stimulation of concanavalin A response was much higher with CRF ligand as compared to Tyr-CRF, CRF-antagonist and sauvagine, and this response was blocked by CRF-antagonist. The lymphocyte proliferative response to stimulation by pokeweed mitogen or monoclonal antibody to CD3 antigen (OKT3) and the activity of natural killer (NK) cells was not affected by CRF. However, this neuroendocrine hormone, in addition to its ability to stimulate lymphocyte proliferation, enhanced expression of interleukin-2 receptors (IL-2R) on T cells (activated T cells) as revealed by a 2-fold increase in the proportion of IL-2R+T cells after the culture of lymphocytes for 3-5 days in the presence of CRF. Based on these findings, we suggest that CRF plays an important role in the modulation of the neuroendocrine-immune circuity.

An 18-mer peptide derived from the retinal S antigen induces uveitis and pinealitis in primates

S-antigen, a photoreceptor cell protein, induces a predominantly T-cell mediated autoimmune uveitis in many vertebrate animals, including primates. Because of this activity and the finding of immune responses to S antigen in patients with uveitis, this protein has been implicated in the pathogenesis of uveitis in humans. Peptide M, an 18-amino acid component of S antigen, has previously been shown to be highly uveitopathogenic in rats and guinea pigs. We report here that peptide M is immunopathogenic in some monkeys, producing inflammatory changes in eyes and pineal glands similar to those induced by native S antigen. Monkeys with disease also developed intense immune responses to peptide M, measured by the lymphocyte proliferation assay. In addition, lymphocytes from these monkeys reacted against whole S antigen. Furthermore, lymphocytes from certain monkeys immunized with whole S antigen responded well against peptide M, thus indicating that this peptide is an immunodominant epitope in these animals. Two of the four monkeys immunized with peptide M did not develop disease. Lymphocytes from these two animals did not respond in culture against the peptide. Following immunization with the whole protein, these monkeys were capable, however, of developing cellular immunity against S antigen and one of them developed disease. The possible involvement of peptide M in the pathogenesis of uveitis in humans is discussed.

Quantitative structure activity relationship studies on 3-triazines using van der Waal volume and molecular connectivity index

QSAR studies have been performed on the homologues of 3-triazines, using molecular connectivity index and van der Waal volume as structural parameters. The regression analysis has shown good correlation between antitumour activity and the two structural parameters.

Rat pineal S-antigen: sequence analysis reveals presence of alpha-transducin homologous sequence

S-antigen (S-Ag) is a soluble, highly antigenic protein, the administration of which induces autoimmune uveitis. This protein is found in the retina and pineal. Retinal S-Ag from three species has been sequenced. In this study rat pineal S-Ag was sequenced. Clones were isolated from a rat pineal lambda gt11 cDNA library by probing with a 300 bp fragment of mouse retinal S-Ag cDNA containing the 5'-coding region. The largest clone isolated (RPS-118; 1364 bp) contained the entire coding sequence. Comparison of the rat pineal and mouse retinal S-Ag nucleotide sequences indicated a high homology (95%). The deduced amino acid sequence was found to contain 403 residues (congruent to 44 992 Da). Comparison of the rat pineal and mouse retinal S-Ag amino acid sequences also revealed high homology (97%). The similarity of both the nucleotide and amino acid sequences of rat pineal and mouse retinal S-Ag indicates that expression of the S-Ag gene in both tissues is similar. Further analysis of the rat pineal S-Ag sequence indicated that it contained essentially the same major uveitopathogenic region of S-Ag present in bovine retina; minor uveitopathogenic sites were somewhat different. As is true of retinal S-Ag, rat pineal S-Ag contains the same consensus phosphoryl-binding site present in many GTP/GDP-binding proteins and a homologous sequence found in the C-terminus of alpha-transducin. These sequences may play a role in the action of pineal S-Ag in transmembrane signal transduction.

Sequence homology between yeast histone H3 and uveitopathogenic site of S-antigen: lymphocyte cross-reaction and adoptive transfer of the disease

Experimental autoimmune uveitis (EAU) serves as an animal model of ocular inflammation. The disease is caused by the immunization of microgram amounts of a soluble retinal protein, designated S-antigen, in susceptible animal strains, including primates. We induced EAU and experimental autoimmune pinealitis (EAP) in Lewis rats with a small synthetic peptide corresponding to amino acid positions 106-121 in yeast histone H3. This peptide contains five consecutive amino acids identical to a uveitopathogenic site (peptide M) in human S-antigen. Lymph node or mononuclear cells from different species of animals immunized either with histone H3 or with peptide M showed significant cross-reaction as measured by in vitro lymphocyte mitogenesis assay using [3H]thymidine. Also, we adoptively transferred the EAU and EAP in naive rats by immune lymph node cells. These findings support the fact that selected bacterial, viral, or fungal proteins with amino acid sequence homologies to normal retinal proteins are uveitopathogenic and, as such, provide a basis for autoimmune inflammatory diseases.

Molecular mimicry. Yeast histone H3-induced experimental autoimmune uveitis

Experimental autoimmune uveitis (EAU) serves as an animal model of ocular inflammation. The disease is caused by the immunization with microgram amounts of a soluble retinal protein, designated S-Ag, in susceptible animal strains, including primates. We induced EAU and pinealitis in Lewis rats with a small synthetic peptide, corresponding to amino acid positions 106 to 121 in yeast histone H3, which contains five consecutive amino acids identical to a uveitopathogenic site in human S-Ag. In addition, native yeast histone was also capable of inducing an EAU in Lewis rats. Lymph node cells from animals immunized with either peptide M (uveitopathogenic site of S-Ag), histone H3 peptide, or native histone showed significant cross-reaction. Also, we adoptively transferred the EAU in naive rats by lymph node cells. These findings provide a basis for studying autoimmune inflammatory diseases of the eye in humans.

Molecular mimicry. Yeast histone H3-induced experimental autoimmune uveitis

Experimental autoimmune uveitis (EAU) serves as an animal model of ocular inflammation. The disease is caused by the immunization with microgram amounts of a soluble retinal protein, designated S-Ag, in susceptible animal strains, including primates. We induced EAU and pinealitis in Lewis rats with a small synthetic peptide, corresponding to amino acid positions 106 to 121 in yeast histone H3, which contains five consecutive amino acids identical to a uveitopathogenic site in human S-Ag. In addition, native yeast histone was also capable of inducing an EAU in Lewis rats. Lymph node cells from animals immunized with either peptide M (uveitopathogenic site of S-Ag), histone H3 peptide, or native histone showed significant cross-reaction. Also, we adoptively transferred the EAU in naive rats by lymph node cells. These findings provide a basis for studying autoimmune inflammatory diseases of the eye in humans.

Fungitoxic studies on bark extract of Lawsonia inermis against ringworm fungi

During screening of barks of 30 plants species against Microsporum gypseum and Trichophyton mentagrophytes, only Lawsonia inermis exhibited absolute toxicity. The Lawsonia bark extract was found to possess fungistatic nature at its maximum inhibitory dilution of 1:30 (W/V) against both the test pathogens but, become fungicidal at 1:10 (W/V). The extract showed broad fungitoxic spectrum when tested against 13 ring worm fungi. Further the fungitoxicity of the extract remained unaltered at high temperature, on autoclaving and after long storage.

Increase of immunoglobulin G3 subclass is related to brain autoantibody in Alzheimer's disease but not in Down's syndrome

The proportions of IgG subclasses (G1, G2, G3 and G4) were quantified in sera from Alzheimer's disease (AD) patients, older Down's syndrome (DS) patients and age-matched controls. The levels of IgG1, IgG2 and IgG4 were normal in AD patients, but the proportions of IgG3 were significantly elevated in 9 of 20 (45%) patients (0.803 +/- 0.141 mg/ml; p less than 0.001) compared to the level found in age-matched controls (0.471 +/- 0.161 mg/ml; n = 10). The IgG3 level in the remaining 11 AD patients was slightly lower than the controls (0.385 +/- 0.104 vs. 0.471 +/- 0.161 mg/ml), but it did not reach statistical significance (p = 0.149). In contrast, patients with DS displayed imbalance of IgG2, IgG3, and IgG4 subclasses; they had significantly increased IgG3 but decreased IgG2 and IgG4 levels. The IgG1 level was within normal range. Moreover, a majority of AD sera (8 of 9) with elevated IgG3 concentration were positive for brain autoantibody. The remaining 11 AD sera without elevated IgG3 level, all DS sera and all control sera were negative for brain autoantibody. This finding indirectly suggests that brain autoantibody is mainly due to IgG3 subclass, at least in one subset of AD patients.

Effects of air-flow limitation on the electrocardiogram in chronic obstructive pulmonary diseases (COPD)

Electrocardiographic studies have been carried out in one hundred and thirty patients of chronic obstructive pulmonary disease (COPD). The possible influence of air-flow limitation, alveolar air trapping, hypoxaemia and hypercapnia on the electrocardiographic findings indicative of right-sided cardiac involvement have been investigated. Thus, the findings: P greater than 2.5 mm, P-axis over +90 degrees, QRS axis over +90 degrees, RV6 less than or equal to 5mm and R/S ratio in V5 V6 less than or equal to 1.0 showed a significant negative correlation with FEV1/FVC ratio. The other features like Ta waves, negative P in AVL, S greater than 5 mm in depth in V5-6 and S1,S2,S3 pattern were observed to be less frequent and correlated weakly with the severity of the disease as judged by the lung function status. The reduction of FEV1/FVC was associated with increased residual volume (air trapping), hypoxaemia and hypercapnia. It is concluded that the ECG changes indicative of right-sided cardiac involvement may be produced by a combination of increased alveolar air trapping and blood gases derangement.

Uveitopathogenic sites in bovine S-antigen

Experimental autoimmune uveitis (EAU) was observed in Hartley guinea pigs following immunization with high doses (200 micrograms) of four synthetic peptides designated peptide 3, K, N and M which correspond to amino acid positions 221-240, 241-260, 281-302, and 303 to 320 respectively in bovine S-antigen. Histopathologically, a moderate inflammatory response involving the uveal tract and retina was observed using peptide N and peptide M as immunogens, whereas peptide 3 and peptide K caused only a mild inflammatory response with very few inflammatory cells in the retina. In contrast, animals with EAU showed an associated pinealitis (EAP) characterized by an extensive lymphocytic infiltration of the central and subcapsular areas of the pineal gland. Lymph node cells of guinea pigs immunized with peptide 3, peptide K, peptide N or peptide M showed strong in vitro proliferative responses against the respective immunizing peptide as measured by [3H] thymidine uptake. The results suggest that under appropriate experimental conditions S-antigen may contain multiple pathogenic sites. The relevance of these studies in the pathogenesis of EAU is discussed.

Identification of a uveitopathogenic and lymphocyte proliferation site in bovine S-antigen

S-antigen is a well-characterized retinal protein that is highly pathogenic for the induction of experimental autoimmune uveitis (EAU), a severe inflammatory disease of the eye and the pineal gland. EAU was observed following the immunization of Lewis rats with various doses (50 to 200 micrograms) of a small synthetic peptide, peptide N (22 amino acids in length), which corresponds to amino acid positions 281 to 302 in bovine S-antigen. Peptide N consistently induced an EAU that was identical to the disease caused by native S-antigen. Clinically, the disease that developed in the eye was characterized by iris and pericorneal hyperemia, followed by inflammatory exudates in the anterior chamber and vitreous. Histopathologically, a severe inflammatory response was observed that resulted in the complete destruction of the photoreceptor cell layer of the retina. In addition, animals with ocular inflammatory disease had an associated pinealitis characterized by a lymphocytic infiltration of the pineal gland. Furthermore, draining lymph node cells of rats immunized with peptide N showed strong in vitro proliferative responses toward peptide N as measured by [3H]thymidine uptake. Our results indicate that several synthetic peptides, which correspond to the amino acid sequence of bovine S-antigen, are capable of inducing an EAU and, as such, suggest that multiple uveitopathogenic sites may be present in the molecule.

Diagnosis of Indian kala-azar by dot enzyme-linked immunosorbent assay (dot-ELISA)

Serodiagnosis of kala-azar was determined by dot-ELISA under variable conditions such as may be encountered in the field, for example, in the nature of the antigen, the preservation of antigen at different temperatures, variation in incubation temperature and so on. The test was found to be useful under field conditions, and the correlation between ELISA and dot-ELISA was significant. Dot-ELISA has definite advantages over the ELISA test, as it is easy to perform, is stable and does not require expensive equipment. The test can be used for large-scale screening of sera in sero-epidemiological studies.

Binding of [125I]corticotropin releasing factor to blood immunocytes and its reduction in Alzheimer's disease

The binding of [125I]iodine-labelled corticotropin releasing factor (CRF) was studied using peripheral blood lymphocytes from normal donors and Alzheimer's disease (AD) patients. The high affinity binding of [125I]CRF was found in the membranes of various immunocytes. Monocytes and T cells displayed binding which was several times greater than the binding of brain (cortical) cells. The immunocyte CRF binding was significantly (P less than 0.001) lower in 14 out of 18 (78%) AD patients relative to non-AD controls, suggesting the association of CRF in the pathology of AD. Our data demonstrate that blood immunocytes can be used to analyze deficiency of neurohormone sites in neuropsychiatric diseases, e.g., AD.

Interferon alters intracellular transport of vesicular stomatitis virus glycoprotein

Double-label immunofluorescence staining studies in virus-infected subclone 11 of LB cells indicated that almost all of the vesicular stomatitis virus (VSV) glycoprotein (G) was plasma membrane-associated during the logarithmic phase of virus replication. In contrast, treatment with interferon (IFN) resulted in inhibition of VSV-G transport, so that almost all of the G remained associated with the Golgi complex (GC) at comparable times after infection. In both IFN-treated and control cells, G was resistant to treatment with the enzyme endo-beta-N-acetylglucosamine H (endo H) indicating that the bulk of the G had reached the trans compartment of the GC.

S-antigen: experimental autoimmune uveitis induced in guinea pigs with two synthetic peptides

Experimental autoimmune uveitis (EAU) was observed in Hartley guinea pigs following immunization with two small synthetic peptides, peptide M and peptide M15L, which correspond to the amino acid sequence of a well-characterized region of bovine S-antigen. Groups of guinea pigs were immunized with 100 micrograms of each peptide in complete Freund's adjuvant and examined at regular intervals for the development of disease. Approximately two weeks later, an EAU was present which was characterized clinically by iris and pericorneal hyperemia. Histopathologically, a severe inflammatory response involving the uveal tract and retina was observed. In these eyes the photoreceptor cell layer of the retina was destroyed. A subretinal exudate containing mononuclear cells and polymorphonuclear leukocytes was also present. In addition, animals with EAU showed an associated pinealitis characterized by a lymphocytic infiltration of the subcapsular and central area of the pineal gland. Furthermore, draining lymph node cells of guinea pigs immunized with peptide M showed strong in vitro proliferative responses towards peptide M as measured by 3H thymidine uptake. These results demonstrate the existence of at least one common pathogenic epitope in bovine S-antigen for the induction of EAU in Hartley guinea pigs and Lewis rats.

Age-related changes in humoral and cell-mediated immunity in Down syndrome children living at home

Abnormalities of humoral and cell-mediated immunity have been described in Down syndrome but reported findings have been inconsistent. Confounding factors have included age, institutional versus home life, hepatitis B antigenemia, and zinc deficiency. To clarify this problem, we studied 64 children with Down syndrome (DS) compared with an age-matched control group. All children had always lived at home. All the DS children were negative for hepatitis B surface antigen. Serum zinc concentration in the DS group was on average 12 micrograms/dl lower than age-matched control children. They also had significantly lower levels of immunoglobulin M, total lymphocyte count, T and B lymphocytes, and T helper and suppressor cells. In vitro lymphocyte response to phytohemagglutinin and concanavalin A was significantly reduced at all ages in the DS group. Lymphocyte response to pokeweed mitogen increased with age in control children but decreased in the DS children. By 18 yr, the mean response for DS was 60000 cpm lower than controls. The DS group had significantly higher concentrations of immunoglobulins A and G than controls and the difference increased with age. Complement fractions C3 and C4 were also higher in the DS group at all ages. The number of HNK-1 positive cells was higher in the DS group than controls at all ages. When hepatitis and institutionalization are excluded as confounding factors, DS children still differ in both humoral and cell-mediated immunity from an age-matched control group.

Progressively decreasing ectopic to second sinus beat intervals in concealed trigeminy

A case of classical concealed trigeminy is reported in which the concealed ventricular extrasystoles occur due to a progressive shortening of the intervals in between manifest extrasystoles and their subsequent conducted second sinus beats. The specific mechanisms underlying such a remarkable phenomenon remain to be explained.

Circadian variation of thyrotrophin, determined by ultrasensitive immunoradiometric assay, and the effect of low dose nocturnal dopamine infusion

The effect of low dose dopamine infusion on the circadian rhythm of thyrotrophin (TSH), prolactin and cortisol in a group of six healthy male volunteers is reported. Subjects were infused in random order with either saline (154 mmol/l NaCl solution; control) or dopamine (0.1 and 1 microgram min-1 kg-1) between 21.00 and 01.00 hours, in random order. The serum TSH profile was characterized by a maximal peak occurring at 23.00 hours and higher nocturnal than diurnal values. Superimposed on this are short term oscillations in serum TSH levels, typical of an ultradian rhythm. The maximal peak in TSH, occurring at 23.00 hours, was abolished by dopamine infused at a rate of 1 microgram min-1 kg-1, and was unaffected by the lower rate of dopamine infusion (0.1 microgram min-1 kg-1). The serum prolactin profile was characterized by a peak occurring soon after the onset of sleep (23.30-00.30 hours), which fell during the morning, and began to rise in late evening. Low dose dopamine (0.1 microgram min-1 kg-1) had a slight but insignificant effect with decreased prolactin levels at the end of the infusion whereas the higher dopamine dose was associated with significantly lower prolactin levels during and throughout the infusion. There was a rebound to levels significantly higher than control on cessation of the infusion. Cortisol levels were unaffected by dopamine.