Markowitz, Harold

Abstract Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) produces chronic demyelination and persistent infection in the central nervous system (CNS) of susceptible SJL mice. This series of experiments examined the contribution of humoral immunity and C to myelin destruction. As in multiple sclerosis, mice persistently infected with TMEV had elevated levels of IgG and oligoclonal bands in the cerebrospinal fluid (CSF). Immunoblot studies revealed that even in animals exhibiting profound demyelination, IgG in the serum and CSF was directed primarily at virus antigen rather than at normal myelin components. Inflammatory cells positive for Ig were distributed mainly around blood vessels, but occasionally they infiltrated the spinal cord parenchyma. Rare examples of myelin sheaths positive for IgG were found by immunoelectron microscopy in spinal cord sections from infected mice; the third component of complement (C3) was commonly found in the walls of CNS blood vessels but not on myelin. Neither serum nor CSF IgG from infected mice bound to myelin sheaths or other CNS components in sections of normal syngeneic spinal cord. There were significantly more demyelinating lesions in infected mice depleted of C components with cobra venom factor. These data do not support a humoral autoimmune basis for the CNS demyelination that occurs in association with persistent TMEV infection. However, the humoral immune response directed at TMEV antigens may either limit virus spread or promote virus persistence.

Abstract Methods have been described for the preparation of serologically active polysaccharides from various strains of H. capsulatum. These polysaccharides were different by chemical analysis, carbohydrate composition, and serologic test by a quantitative C′-fixation technique. Polysaccharides from H. capsulatum cannot be differentiated by use of Con A in the immunodiffusion test. Some differences between these polysaccharides can be shown by quantitative “precipitin” and hemagglutination-inhibition tests. Whether this is due to the relative insensitivity of the reaction with Con A or to only slight differences in configuration among the active sites of the polysaccharides is not presently known.

Abstract Concanavalin A (Con A) has been demonstrated to be antigenic in goats and methods have been described for separating the nonspecific reaction of Con A with polysaccharides from the specific antigen-antibody reaction. Specific precipitating antibody was found to be associated with IgG in the animals studied, and isolated IgG also fixed C′ in the antigen-antibody reaction. The partial inhibition of IgG precipitation of Con A by methyl-α-d-mannopyranoside provides further evidence for the heterogeneity of the immune IgG studied.

Abstract A commercial automated continuous-flow procedure for estimating specific serum proteins has been evaluated for use in determination of IgG, IgA, IgM (both 19S and 7S), α1-antitrypsin, and cerebrospinal fluid proteins. Results of the automated procedure correlate well with manual methods, but are much more precise. Estimation of 7S IgM by the automated method is more accurate than estimation by radial immunodiffusion, because concentrations of 7S IgM are not spuriously elevated.

Abstract A simple unit is described for detecting interrupted flow in an automated immunoprecipitin system. The principle involved is conductivity change resulting from interruption of bubble flow.

Production of precipitating and complement-fixing antibody in rabbits and other animals was induced by immunization with live yeast-phase cells of Histoplasma capsulatum . Results of studies of polysaccharide antigens from three strains of H. capsulatum , by quantitative complement-fixation with human and rabbit antisera, strongly suggest the presence of type specificity. The variations of titer during 11 weeks in one patient with histoplasmosis and the variations of titer among a group of patients with histoplasmosis were studied by use of quantitative complement-fixation tests.

Two strains of mice (C-57 B1 and DBA) were given skin allografts from Swiss ICR/HA mice and were treated with varying doses of concanavalin A; the dosage ranged from only two injections of 25 micrograms during the experiment to daily doses of 1000 micrograms intraperitoneally. Immunosuppression was present at all dosages, the most prolonged and consistent effect being observed at 300 micrograms per day. Grafts survived for 14 to 21 days at this dosage compared to 4 to 9 days for controls.