Toshimasa Nishiyama

Immunodiagnosis of human sparganosis mansoni by micro-chemiluminescence enzyme-linked immunosorbent assay

We compared a microcolorimetric enzyme-linked immunosorbent assay (colorimetric ELISA) and a microchemiluminescence enzyme-linked immunosorbent assay (chemiluminescence ELISA) for the detection of specific immunoglobulin G (IgG) in the serum of 9 patients with sparganosis mansoni and 9 healthy controls. The chemiluminescence ELISA was able to measure serum levels of specific IgG over a far wider range than the colorimetric assay, and its detection limit was at least 10-fold lower. An additional 5 sera from sparganosis patients and 5 more from healthy controls, together with sera from 28 patients with other parasitic diseases, were also examined by the chemiluminescence ELISA. All 14 patients with sparaganosis mansoni showed high levels of chemiluminescence (21,302 +/- 18,907 counts per second [cps]). All sera from the 14 healthy controls (1580 +/- 569 cps) and sera from 27 of the 28 patients with other parasites (4 with taeniasis saginata [1767 +/- 501 cps], 11 with diphyllobothriasis latum [1479 +/- 501 cps], 13 with cysticercosis cellulosae [2376 +/- 1437 cps]) showed chemiluminescence levels lower than those of any of the sparganosis mansoni patients. The exception was a patient with cysticercosis (5980 cps), who may have had a dual infection with Cysticercus cellulosae and Sparganum mansoni. Thus, the chemiluminescence ELISA demonstrated high sensitivity and specificity for human sparganosis mansoni.

Detection of circulating antigens in human trichinellosis

A sandwich enzyme-linked immunosorbent assay was established to detect circulating antigens of Trichinella spiralis in human sera, its sensitivity and specificity was evaluated using 4 antigens (Trichinella spiralis, Trichuris trichiura, Dirofilaria immitis and Ascaris suum), and it was found to be sensitive and specific for T. spiralis antigen. Samples of 347 individuals with suspected trichinellosis, who had eaten incompletely cooked bear meat containing larvae of T. spiralis, were examined. Among individuals showing clinical symptoms, circulating antigens were detected in 29.9%, and the prevalence of antibodies was 18.9%. Among individuals lacking clinical symptoms, antigens were detected in 21.4% and antibodies in 5.0%. It was concluded that detection of circulating antigens was more useful for making diagnoses than measurement of specific antibodies.

Immunocytolocalization study of the external covering of Trichinella spiralis muscle larva.

The antibody-binding sites of the muscle larva of Trichinella spiralis were investigated by immunogold staining on the ultrathin sections of LR white resin. The antibodies, which were produced in the course of T. spiralis infection in rats, specifically bound to the inner layers of the body cuticle and the cuticle of the hindgut, but not to the cuticle of the esophagus. This is the first report that reveals the antigenic nature of the inner layers of the external coverings of T. spiralis larva.

Detection of Soluble T Cell Receptor-Releasing Cells by ELISPOT Assay

A specific and sensitive enzyme-linked immunospot (ELISPOT) assay has been developed for the detection and enumeration of soluble T cell receptor (TCR)-releasing cells. Using this method, we readily detected at the single cell level the release of soluble TCR by living T lymphoma cells (MT-2 and HSB-2) but not by human B lymphoma cells (DAKIKI), mouse hepatoma cells (MH134) and dead MT-2. Furthermore, distinct spots in MT-2 cell culture were not visualized using several monoclonal antibodies against antigens unrelated to TCRs as a primary antibody. The specific and quantitative detection of soluble TCR-releasing cells using ELISPOT assay will certainly provide a valuable tool to better characterize soluble TCRs and their relationship to immune regulation and a number of diseases.

CREEPING DISEASE DUE TO LARVA OE SPIRUROID NEMATODA

A 31‐year‐old man visited our hospital in May 1991, com‐plaining of an abdominal serpiginous eruption with pruritus (Fig. 1). He had eaten raw “firefly squid” (Watasenia scintil‐lans) 2 weeks before the onset of the disease, and the erup‐tion had grown to about 30 cm in length in 2 weeks. The laboratory findings included a leukocyte count of 6100/mm3 with 10% eosinophils and a serum IgE level of 134 U/mL (normal < 303 U/mL). The front of the eruption was excised. Seven parasitic sections were observed in the dermis (Fig. 2). The diameter of the sections were about 0.08 mm. The mus‐cle layer was of the polymyarian coelomyarian type. In the body cavity of the parasite, there was a glandular part of the esophagus composed of vacuolated cells with many nuclei and a narrow esophageal lumen. Well‐developed lateral nerve chords were also visible in these sections. Two of the parasitic sections showed intestine composed of cuboidal cells with a round lumen and lateral nerve chords of both sides touching each other in the center of body cavity.

In vivo interaction between Trypanosoma gambiense and leucocytes in mice

Naturally occurring phagocytosis of Trypanosoma gambiense by mouse eosinophils and neutrophils was reported. In vivo and in vitro experiments using monoclonal antibodies confirmed that the phagocytosis is triggered by G1 class antibodies against variable surface antigen. Ultrastructural observation revealed the mode of entry and the intracellular fate of T. gambiense: initial attachment, pseudopodia formation and complete invagination. This phagocytosis resulted in the killing of T. gambiense by mouse eosinophils and neutrophils, suggesting that eosinophils and neutrophils give at least partial protection against infection with T. gambiense in combination with the specific antibodies.