A freeze-dried paraffin-embedded tissue technique for immunohistochemical studies requiring unfixed tissue from the nervous system

ICAM-1-dependent pathway is not critically involved in the inflammatory process of autoimmune encephalomyelitis or in cytokine-induced inflammation of the central nervous system

To determine whether the rat homolog of intercellular adhesion molecule 1 (ICAM-1) plays an important role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) we examined the effect of anti-ICAM-1 mAb, 1A29, on both active and passive EAE. We also examined its effect on a model of cytokine-induced inflammation in the central nervous system. Treatment of recipients of EAE effector cells with anti-ICAM-1 had no inhibitory activity, and in fact at high doses, treatment enhanced disease as evidenced by an earlier onset of symptoms. Treatment of active EAE with anti-ICAM-1 beginning on the day of sensitization did protect a proportion of animals from development of disease as well as reduce the severity of clinical signs in those which developed symptoms. Lymphocytes from both the draining lymph nodes and spleens of myelin basic protein (MBP)-immunized rats treated with anti-ICAM-1 failed to proliferate in response to MBP in vitro, suggesting that the antibody had prevented the animals from becoming sensitized to the antigen. Microinjection of tumor necrosis factor (TNF)-alpha into the spinal cords of rats led to the expression of ICAM-1 on vascular endothelium, and to the accumulation of leukocytes at sites of injection. The peak expression of ICAM-1 by endothelium and the peak accumulation of leukocytes following TNF alpha injection were not positively correlated. Furthermore, treatment of TNF alpha injected rats with anti-ICAM-1 did not inhibit the accumulation of leukocytes at the site of cytokine injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-idiotypic antibody probes of neuronal nicotinic receptors

Monoclonal anti-idiotypic antibodies specific for the combining site on a monoclonal antinicotine were used in immunocytochemistry to localize nicotine binding sites on rat brain cortical sections and in immunoaffinity chromatography to isolate receptor from solubilized brain tissue. The receptor, which consists of two subunits with Mr values of 43 and 50 kDa, was eluted from the antiidiotype column with either pH3 citrate buffer or 25 mM (-)-nicotine, but was not present in eluates from immobilized anti-Electrophorus acetylcholine receptor or anti-methotrexate. The anti-idiotypes specifically inhibited [3H]nicotine binding to rat brain homogenate and (-)-nicotine inhibited anti-idiotype binding to brain sections based on abrogation of immunofluorescence staining. These results are consistent with the operational definition of the anti-idiotypes as the internal image of nicotine, and demonstrate their value as immunochemical probes of nicotinic receptors.

Methysergide, a serotonin antagonist, does not inhibit the expression of autoimmune encephalomyelitis in the rabbit

In view of recent interest in the potential role of vasoactive amines in the expression of experimental autoimmune encephalomyelitis (EAE) and neuritis (EAN), we set out to determine the effect of slow-release methysergide, a serotonin antagonist, on the effector phase of EAE/EAN in rabbits immunized with homologous spinal cord in Freund's adjuvant. On day 6 post-immunization (p.i.), slow-release pellets of methysergide maleate were implanted subcutaneously in graded doses 0-400 mg. At the highest dose, blood concentrations of methysergide were approximately 90 ng/ml on day 8 p.i. falling to 20 ng/ml by day 16 p.i. However, even at the highest dose of methysergide, rabbits developed typical clinical and histological signs of EAE/EAN. It is concluded that serotonergic mechanisms do not play a critical role in the effector phase of EAE/EAN in the rabbit.

An immunohistological study of autoimmune encephalomyelitis and neuritis in the rabbit. Observations in the dorsal root ganglion using the freeze-dried paraffin-embedded tissue technique

Previous studies of experimental autoimmune encephalomyelitis have shown that, in the central nervous system, the emigration of T-lymphocytes precedes that of mononuclear phagocytes during inflammatory lesion formation. In the present report, the formation of analogous lesions of autoimmune neuritis (EAN) was investigated in the dorsal root ganglia of rabbits immunized with homologous spinal cord in Freund's adjuvant. The relative time course of emigration of T-lymphocytes and mononuclear phagocytes into the ganglia was examined using monoclonal antibody labeling of both types of cells in serial sections of freeze-dried paraffin-embedded tissue. Results indicate that, unlike in the central nervous system, in the rabbit dorsal root ganglion T-lymphocytes and mononuclear phagocytes appear to emigrate simultaneously, as revealed by their concomitant presence in the earliest detectable lesions of EAN. It was also found that the cortical region of the rabbit dorsal root ganglion was a preferential site of EAN lesion formation, and that such lesions correlated well with the onset of clinical signs of paralysis. These results are discussed within the context of known "blood-tissue barriers" and the possible local modulation of inflammatory cell entry into regions of the nervous system.