Uveitis and immune responses in primates immunized with IRBP-derived synthetic peptides

Monkeys immunized with bovine IRBP-derived synthetic peptides R4 (sequence 1158-1180) or R14 (1169-1191) developed EAU which was detected by both clinical and histological examinations. The inflammation localized mainly in the choroid, with only minor changes being noticed in the adjacent retinal tissue. EAU developed in only one of the two monkeys immunized with each of the peptides and the animals with disease also showed higher levels of cellular immunity toward the immunizing peptide than did the monkeys with no disease. The cellular immune responses, measured by the lymphocyte proliferation assay, were specific toward the immunizing peptides, with no cross responsiveness to whole IRBP. This finding suggests that the two uveitogenic peptides were non-immunodominant in the tested monkeys. In contrast, peptide R14 is highly immunodominant in the Lewis rat. Also, the fine specificity of the monkey response to R14 differed from that of the Lewis rat. The possible genetic control of the monkey susceptibility to EAU induction by the peptides is discussed and the unique finding of an autoimmune disease induction by a non-immunodominant peptide is underscored.     

Intradermal capsaicin causes dose-dependent pain, allodynia, and hyperalgesia in humans.

BACKGROUND: Intradermal capsaicin is a human pain model that produces reliable pain and sensitization. This model facilitates controlled testing of analgesic efficacy via a crossover design while minimizing confounding variables in clinical pain states and retaining sufficient power with small samples. METHODS: To determine the lowest dose of capsaicin that produces consistent neurosensory measures, we administered 0.1, 1, 10, or 100 microg to healthy volunteers in a blinded manner (N = 19). Pain scores were recorded at 0, 5, 10, 15, and 60 minutes on a visual analog scale from 0 to 100. Areas and intensities of mechanical allodynia (foam brush stimulus) and pinprick hyperalgesia (von Frey test) were quantified at 15 and 60 minutes, as were flare areas. RESULTS: Capsaicin produced dose-dependent increases in spontaneous pain (p = .013), the area and intensity of mechanical allodynia (p = .006 and p < .001, respectively), the area and intensity of pinprick hyperalgesia (p = .010 and p = .014, respectively), and the flare area (p = .010). The 10 microg dose produced greater spontaneous pain than the 1 microg dose (p = .017). The 100 microg dose produced greater spontaneous pain than the 10 microg, but the difference was not statistically significant. CONCLUSION: The 10 and 100 microg capsaicin doses produced robust pain measures across a range of modalities, and lower doses produced minimal effects. Whereas most studies use 100 microg, using a lower dose is reasonable and may facilitate detection of subtle analgesic effects--particularly with nonopioid analgesics--and drugs can be tested in lower doses, minimizing adverse side effects.     

The relationship between lymphocyte transformation and immune responses. II. Correlations between transformation and humoral and cellular immune responses

Rabbits were immunized against purified proteins, tissue extracts or sheep erythrocytes, with or without Freund's adjuvant. Skin reactions of the delayed type were found only in animals given antigen with adjuvant, although all rabbits developed serum antibodies and most of them Arthus type reactions. Lymphocytes of all animals, however, showed similar transformation activity when cultured with the immunizing antigen.

Thus the blast transformation phenomenon correlates well with both cellular and humoral immune responses and not with the delayed type hypersensitivity only.

     

Selective accumulation of cells with 'B' properties in stimulated lymph nodes.

Draining lymph nodes from mice which had been stimulated with bacterial adjuvants or the skin sensitizing agent, oxazolone, showed a marked increase in cell content, presumably due to lymphocyte immigration. A surprisingly large proportion of these cells exhibit properties of B lymphocytes: the presence of surface Ig, lack of Thy-1-like antigen and responsiveness to lopopolysaccharide (LPS). The relationship between the presence of surface markerand responses to class-specific mitogens, of cells from the stimulated nodes, was established by testing fractionated lymphocyte populations. Enriched T cells did not react to LPS, whereas removal of cells with Thy-1 antigen by specific antisera eliminated the reactions to T mitogens but had little or no effect on the LPS response. The data thus suggest that B cells, which make up a small portion of the circulating lymphocyte pool, are selectively accumulated in lymph nodes stimulated by different immunogens, including T-specific stimulants. This interpretation contradicts the generally accepted assumption, that stimulat lymph nodes trap mostly T lymphocytes.     

Subpopulations of mouse spleen lymphocytes. II. Immunological reactivity of spleen cells fractionated on BSA density gradients.

We found in previous experiments that fractionation of non-immune mouse spleen cells on bovine serum albumin density gradients yields two subpopulations of T cells, one of high, the other of low density. Both subopopulations could be stimulated in corporate thymidine by the T cell-specific mitogen concanavalin A (con A). In the present investigation, spleen cells of mice immunized to sheep red cells (SRC) were similarly fractionated and the fractions recovered were assayed for: (a) reactivity to con A; (B) REACTIVITY TO SRC and (c) capacity to function as helper cells when stimulated with the homologous (SRC) or with a heterologous (donkey red cells) (DRC) antigen. Two subpopulations of cells reacting to con A were found in the spleens of the primed mice, corresponding to the subpopulations found in the non-immune mice. Both subpopulations contained cells responding to SRC (as measured by thymidine incorporation) and cells endowed with helper activity. The two subpopulations appeared to differ, however, in their specificity: while the denser cells could only exert their helper effect when stimulated by the specific antigen, the light cells could be effectively stimulated by both the specific (SRC) and the nonspecific (DRC) antigen.     

Cyclosporin A: alterations of the cellular immune response in S-antigen-induced experimental autoimmune uveitis

We have previously shown that Cyclosporin A (CsA) is effective in preventing S-antigen (S-Ag)-induced experimental autoimmune uveitis (EAU). Lewis rats, which readily develop EAU, were studied for the alterations in cell-mediated immune functions associated with CsA therapy. Lymph nodes draining the site of S-Ag immunization were significantly smaller in the CsA-treated animals when compared to the nonprotected group (p less than 0.01), and also showed profound histologic alterations when compared to controls. In vitro responses of lymphocytes from lymph node and peripheral blood were greatly diminished in the CsA-treated animals. Sera from rats treated with CsA also were capable of inhibiting in vitro proliferative responses. These findings demonstrate that CsA-treated Lewis rats have alterations in several cell-mediated immune functions, thereby not permitting full development of the immune events that ultimately lead to uveitis.     

Heroin self-administration in dependent Wistar rats: increased sensitivity to naloxone

  Rationale: Non-dependent and dependent opiate users appear to be driven by two distinct motivational factors: the primary reinforcing properties of the drug, and the negative reinforcing effects associated with relieving the negative affective component of opiate withdrawal in the dependent state. Objective: To investigate the motivational significance of opioid dependence on heroin self-administration (HSA) in rodents. Methods: Rats were trained to self-administer heroin intravenously (0.06 mg/kg per infusion; FR1), and opiate dependence was induced by subcutaneous implantation of two morphine (75 mg base) pellets.Rats in a non-dependent control group received placebo pellets. Three days after pellet implantation, HSA was resumed in daily 3-h sessions until baseline criteria were met and testing was conducted with subcutaneous injections of vehicle or naloxone (0, 0.003, 0.01, 0.03 mg/kg) 115 min into the session. Results: Morphine-dependent rats significantly increased HSA upon 0.01 mg/kg naloxone treatment, but decreased response rates at 0.03 mg/kg. Placebo pellet-implanted rats increased heroin intake at the 0.01 and 0.03 mg/kg doses. In a second experiment, the HSA session was shortened to 1 h and the training dose reduced to 0.03 mg/kg per infusion in new groups of animals. HSA in placebo pellet-implanted rats was increased only following the highest dose of the antagonist, while dependent rats were still affected by naloxone doses of 0.003–0.03 mg/kg. When subjected to a progressive-ratio schedule (experiment 3), breaking point values in dependent animals were 198% above baseline. Conclusions: The present study supports the hypothesis that dependence-induction by morphine-pellet implant in rats resulted in increased sensitivity to very small naloxone doses, as measured by changes in HSA. Taken together, these data suggest that opiate dependence, as measured by changes in sensitivity to naloxone, is a continuum which can contribute to the motivational state of drug-seeking. Received: 5 June 1998 / Final version: 21 December 1998     

Pain response measured with arterial spin labeling

The majority of functional MRI studies of pain processing in the brain use the blood oxygenation level‐dependent (BOLD) imaging approach. However, the BOLD signal is complex as it depends on simultaneous changes in blood flow, vascular volume and oxygen metabolism. Arterial spin labeling (ASL) perfusion imaging is another imaging approach in which the magnetically labeled arterial water is used as an endogenous tracer that allows for direct measurement of cerebral blood flow. In this study, we assessed the pain response in the brain using a pulsed‐continuous arterial spin labeling (pCASL) approach and a thermal stimulation paradigm. Using pCASL, response to noxious stimulation was detected in somatosensory cortex, anterior cingulate cortex, anterior insula, hippocampus, amygdala, thalamus and precuneus, consistent with the pain response activation patterns detected using the BOLD imaging approach. We suggest that pCASL is a reliable alternative for functional MRI pain studies in conditions in which blood flow, volume or oxygen extraction are altered or compromised. Copyright © 2013 John Wiley & Sons, Ltd.