Studies on antibody formation with enzyme markers

Reverse ELISA for the detection of anti West Nile virus IgG antibodies in humans

We have developed a specific reverse ELISA to investigate the potential of the domain III of the West Nile virus envelope protein to detect virus-specific antibodies. For this purpose, the domain III antigen was expressed in Escherichia coli, refolded and directly labelled with peroxidase. By mixing serum samples with the enzyme-labelled antigen, immune complexes will form that are simultaneously recognized by rheumatoid factor coated microtiter plates. Specific antibodies to the domain III were found in 160 out of 206 sera of patients with neutralising antibodies to West Nile virus (77.6% sensitivity). The antigen differentiated reliably between sera of West Nile virus- and dengue virus-infected patients. In combination with indirect immunofluorescence, to exclude four false-positive samples, the specificity was 100% (280 samples). Assuming a prevalence rate of anti-West-Nile virus antibodies of 5%, the positive and negative predictive values were 93.3% and 98.8% respectively. These results indicate that the reverse ELISA using a specific portion of the envelope antigen of West Nile virus is especially suitable for studies on the prevalence of West Nile infections in affected countries.

The ontogenetic development of the follicular dendritic cell. An ultrastructural study by means of intravenously injected horseradish peroxidase (HRP)-anti-HRP complexes as marker

After intravenous injection of horseradish peroxidase (HRP)-anti-HRP complexes in 21-day-old rats, complex trapping occurs on reticulum cells, forming the stroma of primary follicles of spleens. After intravenous injection of the same complexes in young adult rats (48 days old), trapping occurs on characteristic follicular dendritic cells (FDCs) located in well-developed germinal centers. These results strongly suggest that the follicular dendritic cell originates from a reticulum cell.

Detection of antibody-forming cells and humoral antibody to horseradish peroxidase

Two new simple methods for detecting antibody-forming cells by hemolytic plaque assay and hemagglutinating antibody to horseradish peroxidase have been developed in mice. Both techniques utilize as target, sheep erythrocytes coupled directly with horseradish peroxidase. These assays are sensitive, antigen-specific and are useful to quantitate both direct and indirect antibody-forming cells and humoral antibodies.

An ultrastructural study with enzyme-labeled antibody technique on immunoglobulin-containing cells in human tonsils, especially in germinal centers

Localization of IgG, IgA and IgM in human palatine tonsils, especially in germinal centers, was studied with the electron microscopical enzyme-labeled antibody method. The large germinal center cells differentiate into two kinds of cells within the germinal center; one was the medium-sized germinal center cells not engaging in intracytoplasmic production of immunoglobulins and another was the immature cells producing at least one of the three classes of immunoglobulins, especially IgM. The latter continued to maturate and developed into the intermediate-matured cells and probably into the plasmocytes. The three classes of immunoglobulins were also deposited in the form of admixtures in the intercellular spaces among the constituent cells of the germinal centers, mainly attaching on the cell membrane of desmodendric cells. In addition, some of the deposits were found freely in the intercellular spaces. Some differences between the immunoglobulin-containing cells outside and within the germinal centers were pointed out.