Growth and regression of human tumor cell lines in congenitally athymic (rnu/rnu) rats.

Athymic rats were inoculated with cells from nine human tumor tissue culture cell lines. Tumor growth was seen with seven of the cell lines; histologically, the tumors resembled the tumors from which the cell lines were originated. Only one cell line--a malignant melanoma--grew progressively. The remaining sex cell lines grew to a short period of time and then regressed.

Immunofluorescence and histologic studies of virus-induced murine lymphocytic leukemias.

Mice were inoculated with either the lymphatic leukemia virus associated with Friend and Rauscher viruses or with the Graffi or BALB/Tennant leukemia viruses. A total of 48 leukemic mice were examined histologically and by immunofluorescence. All four viruses induced a histologically similar disease that particularly involved tha thymus-dependent lymphoid regions. Lymphocytes from the spleens and thymuses of leukemic animals were examined for Thy-1 antigen and immunoglobulins on the cell surface; all the leukemias were composed of T- cells and/or nonreactive cells lacking both the Thy-1 antigen and immunoglobulins. By immunofluorescence, the spleen and thymus from the same leukemic animal frequently showed different cell-surface markers, though no morphologic differences were seen in leukemias involving the different classes of lymphocytes.

T-cell lineage of a Friend virus-induced lymphatic leukemia in athymic rats.

Athymic (rnu/rnu) and euthymic rats inoculated with the Friend virus-associated lymphatic leukemia virus developed lymphocytic leukemia. Neoplastic cells from these animals were evaluated by means of indirect immunofluorescence and flow cytofluorometry with monoclonal antibodies Ox-1, Ox-7, and W3/25, which react with surface antigens present on normal rat lymphoid cell populations. Lymphoid cells from leukemic animals revealed characteristic alterations in cell surface fluorescence profiles when compared to normal, healthy controls. Athymic and euthymic leukemic rats were similar in that many cells from both the spleen and bone marrow had markers on the cell surface normally found on thymocytes but not on mature peripheral lymphocytes. These studies provided evidence supporting the presence of T-lineage lymphocytes in the athymic rat. Further, this population of early or "pre"-T-lymphocytes included the predominant leukemia cell type induced by the Friend virus-associated lymphatic leukemia virus.

Erythroid leukemia induced by Friend lymphatic leukemia virus in T-cell-depleted mice.

BALB/c mice depleted of T-cells by thymectomy at 3 to 5 days of age and by treatment with antithymocyte serum were inoculated with the lymphatic leukemia virus derived from Friend virus. After a long latent period, these animals developed erythroid leukemia. In contrast, intact control mice inoculated with Friend virus-associated lymphatic leukemia virus developed typical thymic (T-cell) lymphomas. Cell-free virus prepared from leukemic T-cell-depleted animals induced lymphoid, myeloid, and erythroid leukemias in intact mice. The erythroid leukemia-inducing virus differed from the spleen focus-forming component of Friend virus in its long latent period (88 to 225 days) and in its inability to induce spleen foci. End-point dilution experiments suggested that a hitherto undescribed component of the Friend virus complex might be responsible for these late-appearing erythroid leukemias.

1,25-dihydroxyvitamin D3 receptors in human epithelial cancer cell lines.

Specific, high-affinity cytosolic receptors for 1,25-dihydroxyvitamin D3 have been demonstrated in five human cancer cell lines. The cell lines were derived from tumors of breast, lung, cervix, and melanotic and amelanotic melanomas. Binding affinity (Kd) of the receptors for 1,25-dihydroxyvitamin D3 were all approximately 0.2 nM, and receptor content ranged from 21 to 174 fmol/mg cytosol protein. The receptors from all five cell lines sedimented at 3.2S on sucrose density gradients and exhibited preferential affinity for 1,25-dihydroxyvitamin D3 compared to other vitamin D metabolites.

Dapsone chemotherapy of Mycobacterium leprae infection of the neonatally thymectomized Lewis rat.

In order to learn whether the neonatally thymectomized Lewis rat (NTLR) infected with Mycobacterium leprae could serve as a model for chemotherapeutic studies in a situation resembling that found in human lepromatous leprosy, NTLR inoculated with M. leprae either locally or intravenously 9 to 16 months earlier were treated for from 1.5 to 8.5 months with dapsone (4,4'-diaminodiphenylsulfone, DDS) incorporated in the rat chow in the concentration providing the minimal inhibitory concentration of the drug for M. leprae and in the 100-fold larger concentration. NTLR were killed at intervals; the M. leprae were counted and passed to mice. Treatment with the smaller dosage of dapsone neither killed M. leprae nor reduced the number of organisms in the bacterial populations, whereas treatment with the larger dosage both killed M. leprae and reduced their numbers. The rate at which the organisms were killed (i.e., rendered noninfective for mice) was much the same as that in patients treated with dapsone in comparable dosage. The dead organisms were removed from the rat tissues at a faster rate than encountered in patients. The NTLR may indeed be suitable for chemotherapeutic studies relevant to man. In addition, the more rapid disappearance of dead M. leprae from the rat tissues may facilitate the study of treatment regimens designed to eradicate persisting viable organisms.

Freeze-drying is an effective method for preserving infectious type C retroviruses.

Conventional freeze-drying techniques using a sucrose stabilizer and gelatin can be employed to preserve the infectivity of retroviruses. Lyophilized virus retains its infectivity even at room temperature for more than one year. A lyophilized virus preparation of Friend leukemia virus kept at 4 degrees C for more than 20 years was found to contain high titers of infectious pathogenic virus. This technique offers an easy economic means for shipping type C viruses and for preserving them for long periods of time in the laboratory without the need for cold storage.

Genetic relationship between Treponema pallidum and Treponema pertenue, two noncultivable human pathogens.

Genetic relationships among two strains of Treponema pallidum (Nichols and KKJ) and a strain of T. pertenue were determined by measuring the degree of deoxyribonucleic acid sequence homology. The results in indicated that these three virulent, noncultivable treponemes were genetically indistinguishable. Like T. pallidum (Nichols), T. pertenue (Gauthier) had no detectable deoxyribonucleic acid sequence homology with T. phagedenis (biotype Reiter), T. refringens (biotype Noguchi), or with salmon sperm.

Genetics of Treponema: relationship between Treponema pallidum and five cultivable treponemes.

Three genetically distinct groups of treponemes have been identified by saturation reassociation assays using 125I-labeled treponemal DNAs. The three groups are (i) virulent Treponema pallidum (Nichols strain), (ii) T. phagedenis and its biotypes Reiter and Kazan 5, and (iii) T. refringens biotypes Nichols and Noguchi. There is no detectable DNA sequence homology (less than 5%) among the three groups. The groups have distinct guanine + cytosine contents: 52.4 to 53.7% for T. pallidum, 41.5% for T. refringens, and 38 to 39% for T. phagedenis.

Protection of A/He mice by a Friend virus pseudotype against challenge with Friend virus.

Prior inoculation of 7-wk-old A/He mice with the Graffi pseudotype of Friend virus protected the animals against subsequent challenge with Friend virus. Graffi leukemia virus itself did not induce protection, probably because it failed to replicate in these mice.

Combined rifampin and dapsone chemotherapy of Mycobacterium leprae infection of the neonatally thymectomized Lewis rat.

Neonatally thymectomized Lewis rats (NTLR) were shown to be highly susceptible to infection with Mycobacterium leprae. We have used them in chemotherapeutic studies as models of human lepromatous leprosy. NTLR chronically infected with M. leprae were treated with various regimens combining a background of the minimal effective dose (MED) of dapsone (4,4'-diaminodiphenylsulfone, DDS) or 100 times this dose in the diet with one to ten doses of rifampin (RMP) of 10 mg/kg. To test for persisting viable M. leprae passage of 5 X 19(3) organisms was made to intact mice, and 10(5) to 10(7) acid-fast bacilli were passaged to NTLR. The only regimen that appeared to be completely effective in eliminating infectivity for intact mice was ten doses of RMP given on the background of the MED of DDS. No viable organisms were detected in any passage mice, but multiplication of M. leprae was detected in 12 of 16 passage NTLR, representing three of the four groups in which passage was made. In no instance did we fail to detect organisms in passage of NTLR when we detected them in passage mice, and multiplication was demonstrated in passage NTLR in 14 instances in which M. leprae failed to multiply in passage mice. Because of its high degree of immunosuppression, the NTLR was able to detect a small population of viable M. leprae in inocula containing up to 5000 times the number of organisms that can be inoculated into intact mice. The NTLR appears to provide a model for the study of microbial persistence in leprosy.

Neonatally thymectomized Lewis rats infected with Mycobacterium leprae: response to primary infection, secondary challenge, and large inocula.

Several experiments were carried out to measure the ability of neonatally thymectomized Lewis rats (NTLR) to limit multiplication of Mycobacterium leprae. NTLR inoculated in one hind footpad with 10(7) viable M. leprae and challenged in the other hind footpad with 5 x 10(3) organisms simultaneously or 120 or 180 days later permitted multiplication in both sites. By contrast, immunologically intact rats similarly inoculated did not permit multiplication from either inoculum. NTLR and immunologically normal BALB/c mice were equally susceptible to infection with M. leprae, in that multiplication occurred regularly in the footpads of both species when inoculated with a bacterial suspension diluted to provide five organisms per footpad. Finally, multiplication occurred when five viable M. leprae diluted with 10(7) heat-killed organisms were inoculated into the footpads of NTLR. Although there was some evidence that NTLR are not completely immunosuppressed, NTLR appear to be capable of detecting much smaller proportions of viable M. leprae than can be detected by immunologically normal mice.