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Immunologic studies on myasthenia gravis. II: A new chemotactic factor for lymphocytes found in patients with
1First Department of Surgery, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
A specific chemotactic factor for lymphocytes was found in thymic tissue extract from myasthenic patients who had undergone thymectomy. Biologic activities and the biochemical nature of this factor were examined. The major findings were as follows: (1) The factor from myasthenic thymus was specifically chemotactic for T lymphocytes. Marker analysis of target cells revealed that only OKT4 positive cells (helper/inducer T cells) responded to the factor. Chemotactic activity was also found in the normal thymus, but its activity was different from that found in the myasthenic thymus. Interestingly, OKT8 positive cells (suppressor/cytotoxic T cells), as well as OKT4 positive cells, migrated toward the normal thymic extract (2) Chromatography of the extract by gel filtration gave three peaks with chemotactic activity; molecular size were 160,000 to 100,000, 25,000 to 15,000, and smaller than 1350 daltons (3) The factor was inactivated by heating for 30 minutes at 56 degree C and was also destroyed under conditions of pH 4 and pH 10. The factor was also sensitive to treatment by trypsin, sodium metaperiodata, 8 mol/L urea, reduction, or alkylation. (4) The chemotactic activity in the myasthenic thymus was distinct from other known chemotactic factors, including C5a, interleukin-1, and interleukin-2. (5) Chemotactic activity for lymphocytes was found in both the aqueous extract and the culture supernatant of thymic stromal cells, but not in thymocyte extract or in the serum. These findings indicate that the chemotactic factor specific for OKT4 positive cells may be secreted by stromal cells of the myasthenic thymus but not of the normal thymus.
A specific chemotactic factor for lymphocytes was found in thymic tissue extract from myasthenic patients who had undergone thymectomy. Biologic activities and the biochemical nature of this factor were examined. The major findings were as follows: (1) The factor from myasthenic thymus was specifically chemotactic for T lymphocytes. Marker analysis of target cells revealed that only OKT4 positive cells (helper/inducer T cells) responded to the factor. Chemotactic activity was also found in the normal thymus, but its activity was different from that found in the myasthenic thymus. Interestingly, OKT8 positive cells (suppressor/cytotoxic T cells), as well as OKT4 positive cells, migrated toward the normal thymic extract (2) Chromatography of the extract by gel filtration gave three peaks with chemotactic activity; molecular size were 160,000 to 100,000, 25,000 to 15,000, and smaller than 1350 daltons (3) The factor was inactivated by heating for 30 minutes at 56 degree C and was also destroyed under conditions of pH 4 and pH 10. The factor was also sensitive to treatment by trypsin, sodium metaperiodata, 8 mol/L urea, reduction, or alkylation. (4) The chemotactic activity in the myasthenic thymus was distinct from other known chemotactic factors, including C5a, interleukin-1, and interleukin-2. (5) Chemotactic activity for lymphocytes was found in both the aqueous extract and the culture supernatant of thymic stromal cells, but not in thymocyte extract or in the serum. These findings indicate that the chemotactic factor specific for OKT4 positive cells may be secreted by stromal cells of the myasthenic thymus but not of the normal thymus.