Two different types of cells in the peritoneal cavity of mice produce mast cell colonies in methylcellulose. “Large” mast cell colonies are produced by bone marrow-derived precursors resembling lymphoid cells by light microscopy (L-CFU-Mast), whereas “medium” and “small” mast cell colonies are produced by morphologically identifiable mast cells (M-CFU- Mast and S-CFU-Mast, respectively). In the present study we eradicated peritoneal mast cells by intraperitoneal (IP) injection of distilled water. The regeneration process was investigated to clarify the relationship between L-CFU-Mast, M-CFU-Mast, and S-CFU-Mast. After injection of distilled water, M-CFU-Mast and S-CFU-Mast disappeared, but L-CFU-Mast increased, and then M-CFU-Mast and S-CFU-Mast appeared, suggesting the presence of a hierarchic relationship. When purified peritoneal mast cells were injected two days after the water injection, the L-CFU-Mast did not increase. In the peritoneal cavity of WBB6F1-+/+ mice that had been lethally irradiated and rescued by bone marrow cells of C57BL/6-bgJ/bgJ (beige, Chediak-Higashi syndrome) mice, L-CFU-Mast were of bgJ/bgJ type, but M-CFU-Mast and S-CFU-Mast were of +/+ type. The injection of distilled water to the radiation chimeras resulted in the development of bgJ/bgJ-type M-CFU-Mast and then S-CFU-Mast. The presence of mast cells appeared to suppress the recruitment of L-CFU- Mast from the bloodstream and to inhibit the differentiation of L-CFU- Mast to M-CFU-Mast.

Two different types of cells in the peritoneal cavity of mice produce mast cell colonies in methylcellulose. “Large” mast cell colonies are produced by bone marrow-derived precursors resembling lymphoid cells by light microscopy (L-CFU-Mast), whereas “medium” and “small” mast cell colonies are produced by morphologically identifiable mast cells (M-CFU- Mast and S-CFU-Mast, respectively). In the present study we eradicated peritoneal mast cells by intraperitoneal (IP) injection of distilled water. The regeneration process was investigated to clarify the relationship between L-CFU-Mast, M-CFU-Mast, and S-CFU-Mast. After injection of distilled water, M-CFU-Mast and S-CFU-Mast disappeared, but L-CFU-Mast increased, and then M-CFU-Mast and S-CFU-Mast appeared, suggesting the presence of a hierarchic relationship. When purified peritoneal mast cells were injected two days after the water injection, the L-CFU-Mast did not increase. In the peritoneal cavity of WBB6F1-+/+ mice that had been lethally irradiated and rescued by bone marrow cells of C57BL/6-bgJ/bgJ (beige, Chediak-Higashi syndrome) mice, L-CFU-Mast were of bgJ/bgJ type, but M-CFU-Mast and S-CFU-Mast were of +/+ type. The injection of distilled water to the radiation chimeras resulted in the development of bgJ/bgJ-type M-CFU-Mast and then S-CFU-Mast. The presence of mast cells appeared to suppress the recruitment of L-CFU- Mast from the bloodstream and to inhibit the differentiation of L-CFU- Mast to M-CFU-Mast.

We describe a case of cardiac myxoma in a 44-year-old Japanese man, who died after developing metastases in the skin, brain and muscle. A satellite tumor which was attached to the wall of the abdominal aorta induced marked hypertension due to obstruction of the renal arteries. Although the primary heart tumor had typical histological features of benign cardiac myxoma, the recurrent heart tumor, which was partly resected three months before the patient's death, showed apparently malignant characteristics resembling malignant fibrous histiocytoma (MFH).Since the histological features of the initial and recurrent tumors were different, the grade of malignancy was investigated using the cellularity of the tumor as an arbitrary criterion. A gradual but significant increase in the cellularity was observed over the course of five years. Immunohistochemically, tumor cells i n the muscle metastasis contained vimentin and factor VIII-related antigen, and multinucleated giant cells in the recurrent heart tumor contained desmin, which is rarely detectable in MFH. Therefore, we considered that the present case represented malignant transformation of benign cardiac myxoma. Acta Pathol Jpn 40 : 687-692, 1990.

The potential to reconstitute the whole erythropoiesis of a genetically anemic (WB X C57BL/6)F1-W/Wv (WBB6F1-W/Wv) mouse for at least 8 weeks was compared between 5-fluorouracil (5FU)-treated and nontreated bone marrow cells. C57BL/6-Pgk-1b/Pgk-1a female mice, in which each stem cell had either A-type or B-type phosphoglycerate kinase (PGK) owing to the random inactivation of one of two X chromosomes, were used as donors. As a marker of the reconstitution, electrophoretic pattern of hemoglobin was used. The concentration of the stem cells that reconstitute the whole erythropoiesis of WBB6F1-W/Wv mouse was higher in the marrow of donors that had received an injection of 5FU two days previously (two-day 5FU-treated) than in the marrow of nontreated donors. In the marrow of four-day 5FU-treated mice, however, the concentration was comparable to that of nontreated mice. The PGK electrophoretic pattern of WBB6F1-W/Wv mice reconstituted by nontreated marrow cells was comparable to the PGK pattern of WBB6F1-W/Wv mice reconstituted by four-day 5FU-treated marrow cells. Thus, a single stem cell with extensive proliferative potential rather than multiple spleen colony-forming units appeared to be responsible for the erythropoietic reconstitution in the transplantation of nontreated healthy marrow cells as well as 5FU-treated marrow cells.

We investigated whether the stem cell that reconstitutes total erythropoiesis of a WBB6F1-W/Wv mouse differentiates into lymphoid lineage. The electrophoretic pattern of hemoglobin was used as a marker of the reconstitution; 3-phosphoglycerate kinase (PGK), an X chromosome- linked enzyme was used as a tool for estimating clonality. We injected 10(5) bone marrow cells of 5-FU treated C57BL/6-Pgk-1b/Pgk-1a female mice, in which each stem cell had either A-type PGK or B-type PGK due to random inactivation of one of two X chromosomes, into genetically anemic (WB x C57BL/6)F1-W/Wv (hereafter WBB6F1-W/Wv) mice that contained only B-type PGK. The recipient WBB6F1-W/Wv mice, in which erythropoiesis was reconstituted with donor cells for a long term, were killed and the PGK patterns of bone marrows, thymus, lymph nodes, and Peyer's patches were examined. A considerable amount of A-type PGK was detected in the lymphoid organs of the WBB6F1-W/Wv mice in which erythrocytes showed only A-type PGK when killed. In contrast, A-type PGK was scarcely detectable in the lymphoid organs of the WBB6F1-W/Wv mice in which erythrocytes showed only B-type PGK when killed. The present results suggest that the hematopoietic stem cells estimated by the erythropoiesis reconstituting assay differentiate into lymphoid lineage and that the long-term erythropoiesis reconstitution assay is useful for detecting the true primitive hematopoietic stem cells.