Noriko Tomita

Transformation of CD8 + T‐Cells Producing a Strong Cytopathic Effect on CD4+ T‐Cells through Syncytium Formation by HTLV‐II

Human T‐cell leukemia virus type II (HTLV‐II) is thought to play an important role in the development of CD8 + T‐cell malignancies resembling hairy cell leukemia. In this study, dramatic cytopathic effects characterized by syncytium formation in various CD4+ T‐cell lines were observed upon their cocultivation with HTLV‐II infected T‐cells. The HTLV‐II infected T‐cells, however, did not die as a result of syncytium formation. HTLV‐II also transformed CD4 + T‐cells and CD8 + T‐cells at various coculture ratios. Furthermore, sera from antiHTLV‐II antibody‐positive specific carriers inhibited syncytium formation in the CD4+ T‐cells. These results suggest that HTLV‐II infection may contribute to the pathogenesis of associated CD8 + T‐cell malignancies.

HTLV‐II Non‐integrated Malignant Lymphoma Induction in Japanese White Rabbits Following Intravenous Inoculation of HTLV‐II‐infected Simian Leukocyte Cell Line (Si‐IIA)

Lymphoma induction in rabbits by an unknown factor derived from an HTLV‐II‐producing simian (Cynomolgus) leukocyte cell line (Si‐IIA) is reported. Thirteen of 17 male Japanese white rabbits (76%) inoculated intravenously with Si‐IIA cells developed malignant lymphoma including Hodgkin‐like lymphoma between 62 and 167 days after inoculation. Historically, there was extensive diffuse or nodular infiltration of either large cell type or mixed type lymphoma cells in many organs, frequently involving the spleen, liver, lymph nodes and kidneys, and less frequently the thymus, bone marrow, lungs, heart, skin and gastrointestinal tract. Hodgkin‐like lymphoma was also observed in two rabbits. Chromosomal analysis of five cell lines established from tumor‐bearing rabbits revealed the male rabbit karyotype. The immunophenotype of these tumor cells was usually T‐cell (CD5+or, r RT1+, RT2+or‐, CD45+, CD4−, RABELA− and MHC class II‐DQ+) except for Hodgkin‐like lymphoma cells which expressed only CD45. However, integration of the HTLV‐II provirus genome could not be demonstrated in the tumor tissues or any of the rabbit cell lines by polymerase chain reaction or Southern blot analysis. Moreover, no lymphoma was induced by inoculation of HTLV‐IIC, MOT (other HTLV‐II‐producing human cell lines) or TALL‐1 (control). Two of four rabbits injected with cell‐free pellets from Si‐IIA cultures died of malignant lymphoma (15‐20 days). Five irradiated rabbit cell lines were inoculated but only one (Ra‐SLN) induced lymphoma in 1 of 3 rabbits at 27 days. Neither Herpesvirus saimiri nor Herpesvirus ateles (simian oncogenic viruses) was detected in Si‐IIA cells by immunofluorescence testing. These data suggest that the high rate of lymphoma induction in rabbits may be caused not by only HTLV‐II or well known simian oncogenic viruses, but rather by an unknown passenger agent derived from Si‐IIA or HTLV‐IIA, with which Si‐IIA was established.

Co-expression of CD4 and CD8 associated with elevated interleukin-4 in a cord T cell line derived by cocultivating normal cord leukocytes and an HTLV-II-producing simian leukocyte cell line (Si-IIA)

SummaryA new interleukin-2(IL-2)-dependent T cell line, designated CS-IIA, was established by cocultivating normal human cord leukocytes and a lethally X-irradiated HTLV-II-producing simian leukocyte cell line (Si-IIA). CS-IIA showed CD4 dominance during the early culture. However, after addition of IL-2, CS-IIA predominantly co-expressed CD4 and CD8 (69.5%) and also expressed the surface markers CD1−, CD3+, CD19−, CD25+ and HLA-DR+. A significantly elevated level of IL-4 (1697 pg/ml) was observed in the culture supernatant from CS-IIA. In addition, the conversion of phenotype from some CD4+CD8+ cells to CD4+CD8− was demonstrated by the neutralization assay using anti-IL-4 antibody. CS-IIA had a normal human karyotype and was free from Epstein-Barr virus nuclear antigen and immunoreactive with sera of HTLV-I- or HTLV-II-infected patients and anti-HTLV-1, p19 or p24 mAb. The provirus genome of HTLV-II was detected in this cell line by the polymerase chain reaction combined with a digoxigenin-enzyme-linked immunosorbent assay. However, electron microscopy of CS-IIA cells revealed no C-type virus particles in the extracellular space. These results indicate that HTLV-II can be transmitted from an HTLV-II-infected simian leukocyte cell line to human cord T lymphocytes and suggest that co-expression of CD4 and CD8 on T cells may be induced by the high level of IL-4, which can mediate CD8 induction on CD4+ T cell clones.

HTLV-II-specific antisera raised in rabbits immunized with a synthetic peptide of HTLV-II envelope protein

SummaryIn order to discriminate HTLV-II from HTLV-I, HTLV-II-specific polyclonal antibodies against a synthetic peptide of HTLV-II envelope sequence were raised in rabbits. We immunized two adult rabbits with a KLH-conjugated synthetic peptide corresponding to the amino acid sequence 171–196 of the HTLV-II envelope sequence, which is a specific region for HTLV-II as evaluated with an ELISA method. The resulting rabbit antisera to the synthetic peptide reacted with gp46 of HTLV-II lysates in Western blot analysis, but not with that of HTLV-I. Flow cytometric analysis and immunohistochemical study revealed that these affinity purified antisera recognized some HTLV-II-producing cell lines examined, but not HTLV-I-producing cell lines or other cell lines uninfected by HTLV. These findings indicate that these antisera specifically recognized the envelope glycoprotein (gp46) of HTLV-II and suggest the specificity of this region in the immune response to HTLV-II. Such antisera are useful in distinguishing between HTLV-I and HTLV-II infection and in determining the presence of individual HTLV-II-infected cells both in vivo and in vitro, including non-lymphoid cells. They may also assist in the elucidation of the pathogenesis of HTLV-II.

A B-CELL LINE HAVING CHROMOSOME 14 ABERRATION AT BREAK BAND qll DERIVED FROM AN ADULT T-CELL LEUKEMIA PATIENT

A B‐cell line having translocations of chromosome 14 at break band q11 (the assigned locus of the α‐chain gene of the T‐cell antigen receptor) and chromosome 3 at break band p25 (the assigned locus of the c‐raf‐1 oncogene) was established from peripheral blood leukocytes of an adult T‐cell leukemia (ATL) patient. The same chromosome 14 aberration at break band q11 and chromosome 3 aberration at break band p25 were also found in fresh T‐cell leukemia cells. The B‐cell line is surface immunoglobulin (sIg)+, immunoglobulin gene rearrangement+, ATL‐specific antigen (ATLA)+, HTLV‐1 proviral genome+, Epstein‐Barr virus (EBV)‐associated nuclear antigen (EBNA)+ and the EBV DNA genome+. The fresh T‐leukemic cells were T‐cell receptor gene rearrangement+, the HTLV‐1 proviral genome+ and EBV DNA genome−.