Subcutaneous (s.c.) inoculation of the 85-4LN subline, derived from a lymph nodal metastasis of the Epstein-Barr virus (EBV) transformed human chronic lymphocytic leukemia (CLL) B cell line, EBV-CLL (1), produced progressively growing lethal tumors in 31/35 nonirradiated (88.6%) and 22/25 (88%) of whole-body irradiated (440 rad) nude mice. In contrast, EBV-CLL(1) could produce progressive tumors only in irradiated nude mice. All 85-4LN cells had Epstein-Barr virus nuclear antigen and reacted with pan B and anti-la antibodies. The morphology and ultrastructural features was consistent with the lymphoblastoid nature of the cells. In all s.c. tumor bearing mice, there was enlargement of the spleen and draining lymph nodes. Karyological studies revealed human cells in the spleen and draining nodes in all the mice investigated. Metastases in nonlymphoid organs were seen in 1/8 irradiated and 8/12 nonirradiated mice. The subline contained 77% cells with 47,XY, +12 and 23% cells with 45,XY karyotype. The clone with trisomy 12 did not have any growth advantage either in s.c. transplants or in splenic/lymph nodal metastases. Treatment with the maximum permissible doses of methotrexate (MTX) or chlorambucil (CBL) revealed xenografts to be more sensitive to MTX than CBL. A clone with a 1g+ marker, i.e., 46,XY,Dup(1) (q11----q32) appeared to be associated with resistance to CBL. We have not seen any previous report on the growth and dissemination of human CLL B cells in nonirradiated nude mice. The 85-4LN subline, thus, provides a model for studying the progression, dissemination and therapeutic response of human CLL-B cells.

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The G-band pattern in 445 metaphases obtained seven weeks after irradiation (600 rad gamma-ray) was analysed. Approximately 37% of these cells had one or more structural aberrations. The majority of the aberrant events was reciprocal translocation followed by inversion and deletion in the proportion of 9:1:1 respectively. Statistical analyses (Chi-square tests) on the distribution of breakpoints among chromosomes showed an excess number of breaks in chromosomes 1, 7, and 12. Chromosomes 1 and 12 were particularly involved in cells carrying multiple aberrations while chromosome 7 was preferentially involved in deletion. Within chromosomes a significantly large number of breaks were located in (a) the light bands and (b) the terminal segments. The significance of these findings is discussed.

A clone of Vero cells resistant to up to 20 micrograms/ml 8-azaguanine was isolated. This clone (designated Vero 153) has a doubling rate of approximately 24 h and a maximum cell density of 10,000/mm2. Deficiency of the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT) in Vero 153 was demonstrated by methods of radiochromatography. Vero 153 is susceptible to hypoxanthine-thymidine-aminopterin (HAT) medium and its resistance to 8-azaguanine seems to be nonreversible. Like parental cells, Vero 153 was also incapable of interferon production when challenged with Newcastle disease virus (NDV) or poly(inosinic acid) . poly(cytidylic acid) (poly I:C). Similar chromosome complements (majority range 56 to 57) and band patterns were observed in cells harvested at Passages 10, 20, and 50. The potential use of Vero 153 for somatic cell hybridization for purposes of gene mapping, virus rescue, and the control of interferon production is discussed.

A Vero cell line (Vero 153) resistant to 8-azaguanine and unresponsive to viral induction of interferon was isolated. This primate (African green) cell line was fused with mouse myeloma (S194/5) and normal human lymphocytes from peripheral blood. All Vero 153--mouse hybrids, 8 primary and 12 secondary clones, produced virus-induced mouse but not primate interferon. This occurred even in cultures where greater than 90% of primate chromosomes were retained. Similarly 7 primary and 3 secondary Vero 153--human clones synthesized virus-induced interferon. This could be neutralized by anti-human fibroblast (beta) but not by anti-human leukocyte (alpha) interferon antisera. The unresponsive nature of Vero 153 cells to interferon induction by viruses was not changed by the presence of interferon producing genomes from other cells. However, despite the inability to produce interferon, the Vero cell was able to play a role in the determination of the type of interferon made in the hybrid cell.