Important note: Information in this article was accurate in 1993. The state of the art may have changed since the publication date.
A study of polyoma virus-induced murine thymic epithelial tumors: a model of the thymic microenvironment.
Diss Abstr Int [B]; 52(8):4112 1992. Unique Identifier : AIDSLINE ICDB/93682284 Hoot GP; Univ. of Texas Health Science Center at Dallas
Abstract:
A strain of polyoma virus, PTA, induced multiple epithelial tumors when injected into neonatal C3H/Bittner mice, especially thymic epithelial and salivary epithelial tumors. Neoplastic thymic epithelium was found to coexpress ER-TR4 and ER-TR5 markers, which are mutually exclusive on normal thymic cortical and medullary epithelium, respectively. The neoplastic epithelium showed heterogeneous expression of Ia, H-2K, and asialo-GM1. Islands of normal cortical thymocytes were interspersed in primary tumors. Rarely, medullary areas, defined by presence of interdigitating cells, were found. Lymphocytes in the tumors phenotypically resembled normal thymocytes with CD4+CD8+, CD4+CD8-, and CD4-CD8+ subsets, although, there was some variability in the ratio of subsets compared with normal thymus. Tumor thymocytes were in active cell cycle. Glucocorticoid treatment caused acute thymic involution in thymomas similar to normal thymus. Model variation in epitope density on thymoma-derived thymocytes was observed for Thy 1, PNA, Lyt-1, and H-2K(K). Functional immaturity of thymoma-derived thymocytes was shown in mitogen-induced proliferation assays. Thymic nurse cell complexes were not isolated from primary thymomas. Mature lymphoid subsets in spleens were unaffected in animals which developed thymomas. Approximately 25% of primary salivary gland epitheliomas, which arose in the virally infected C3H/Bittner mice, were infiltrated with lymphocytes. These lymphocytes were in active cell cycle and had immature surface phenotype like normal thymocytes. Because the CD4+CD8+ subset does not recirculate through blood, it appeared that some primary salivary epitheliomas were functioning like a thymus. A few thymic epitheliomas were established as serially transplantable solid tumors; salivary epitheliomas easily established as transplantable solid tumors. Passageable salivary epitheliomas arose which routinely showed heavy lymphocytic infiltration. These tumors had neoplastic epithelial and normal lymphoid components similar to primary thymomas. By relying on allelisms at Thy 1 and Lyt-2 loci, tumors in F1 mice were shown to be infiltrated with thymocytes of host rather than tumor origin. This established that neoplastic thymoma epithelium was capable of maintaining a thymic-like microenvironment. However, no mature lymphocytes were ever found in spleens of nude mice, showing that intratumor 'thymocytes' were incapable of seeding the mature peripheral lymphoid compartment. A possible relationship of neoplastic salivary and thymic epitheliomas to ectodermally derived normal cortical epithelium is discussed. (Abstract shortened with permission of author.)
Keywords: Animal Carcinoma/IMMUNOLOGY/*MICROBIOLOGY/PATHOLOGY CD4-CD8 Ratio G(M1) Ganglioside/ANALYSIS H-2 Antigens/ANALYSIS Histocompatibility Antigens Class II/ANALYSIS Mice Mice, Inbred C3H *Polyomavirus Salivary Gland Neoplasms/IMMUNOLOGY/*MICROBIOLOGY/PATHOLOGY Thymoma/IMMUNOLOGY/*MICROBIOLOGY/PATHOLOGY Thymus Neoplasms/IMMUNOLOGY/*MICROBIOLOGY/PATHOLOGY THESIS 930730
M9371002
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Important note: Information in this article was accurate in 1993. The state of the art may have changed since the publication date.
