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Biomedical subjects

C W Stackpole

Publications and source records attributed to C W Stackpole.

At least 37 records · Page 2Linked to original sources
PubMed1980

Modulation of thymus-leukemia antigens on mouse leukemia cells induced by IgG, but not IgM, antibody.

Exposure of mouse leukemia cells bearing thymus-leukemia (TL) surface antigens to whole TL alloantiserum has previously been shown to desensitize the cells to subsequent lysis by guinea pig complement (C) and fresh antiserum (antigenic modulation) and to correlate with the ability of cells to escape immune destruction in mice immunized against TL antigens. Tested in vitro, IgG of TL.1,2,3,5 antiserum modulated RADA1 leukemia cells (TL.1,2,3,5) completely within 2 hours at 37 degrees C when fully sensitizing amounts were used, with normal mouse serum as a source of C3. Similar results were obtained with IgG1, IgG2a, and IgG2b fractions of TL antiserum. An IgG2a monoclonal TL.3 antibody also completely modulated TL.3 antigens and partially modulated all antigens detected with TL.1,2,3,5 antiserum. IgM anti-TL.1,2,3,5 failed to modulate RADA1 cells even after 6 hours in vitro when fully sensitizing amounts of antibody were used. An IgM monoclonal TL antibody also failed to induce modulation. Modulation did occur on cells incubated with fully sensitizing amounts of IgG and IgM TL.1,2,3,5 antibody simultaneously, and nearly all cell-bound immunoglobulins were IgG. In mice passively immunized with IgG TL antibody, RADA1 cells modulated completely within 24 hours, whereas no modulation occurred during 4 days in mice immunized with IgM antibody. However, in both instances, tumor cells grew actively, which indicated that tumor escape did not depend on achievement of a modulated state.

Animals↗
PubMed1979

Metrizamide gradient purification of mouse tumor cells.

A one-step isopycnic density gradient centrifugation procedure is described for purification of highly viable and homogeneous tumor cells from a variety of solid mouse tumors. Mechanically suspended cells are layered onto preformed continuous gradients of medium 199-buffered 7--33% metrizamide (density range 1.05--1.20 g/cu. cm) isoosmotic with mouse plasma and centrifuged for 30 min. Large numbers of tumor cells, generally 85--95% viable and free from 80--95% of contaminating host lymphoid and phagocytic cells and erythrocytes, were consistently recovered from fractionated thymomas, melanomas, and fibrosarcomas. By a variety of criteria, cell surface and other biological properties of gradient-purified tumor cells were normal.

Animals↗
PubMed1979

Antigenic modulation in vitro. III. Failure to modulate H-2 antigens on several mouse tumors.

The capacity of various malignant and normal mouse cells to acquire resistance to lysis by guinea pig complement during exposure to H-2 antisera in vitro at 37 degrees C (antigenic modulation) was examined. All tumors tested, including cell lines of the TL+ leukemias RADA1, ASL1, and RLmale1, the TL- leukemia EL 4, myelomas MOPC-70A and S194, and the sarcoma Meth A, failed to modulate when incubated with multispecific or monospecific H-2 antisera up to 24 hours, even though under comparable conditions thymus-leukemia (TL) antigens and surface IgG molecules modulated within several hours. Indirect sensitization of RADA1 leukemia cells with H-2 antisera followed by antiserum against mouse IgG also failed to induce H-2 antigen modulation. Normal peritoneal cells from certain mouse strains were partially modulated with H-2D-specific or H-2K-specific and monospecific antisera within several hours, but normal thymus and lymph node cells did not modulate. Modulation of peritoneal cells occurred without a complete loss of sensitizing H-2 antibody from the cell surface and required a cobra venom factor-sensitive activity that could be restored by human complement component C3. Modulation of TL antigens in vitro had previously been shown to have similar characteristics.

Animals↗
PubMed1979

Serum requirements for in vivo modulation of thymus-leukemia antigens on mouse leukemia cells and thymocytes.

Mouse leukemia cells and normal thymocytes bearing thymus-leukemia (TL) cell surface antigens were previously shown to acquire resistance to lysis by guinea pig complement (C) during incubation with TL alloantiserum in vitro at 37 degrees C due to heat-labile serum activity resulting in deposition of mouse C3 onto the cell surface. The role of heat-labile serum activity and C3 in modulation of TL+ cells in vivo in mice actively or passively immunized against TL antigens was investigated. Mice of the TL-/TL+ C57BL/6J (B6) strain and the B6 congenic strain B6-Tiaa possessed poorly modulating sera, and the radiation-induced A-strain leukemia RADA1 transplanted into B6 mice passively immunized with heated (56 degrees C) TL antiserum failed to modulate; thymocytes of B6-Tiaa mice immunized similarly also did not modulate. A specific requirement for mouse C3 deposition onto RADA1 cells to achieve a modulated state was demonstrated in actively immunized TL- (B6 X A-Tiab)F1 mice in which circulating C3 and modulating activity were depleted by administration of cobra venom factor. In immunized (B6 X A-Tiab)F1 mice bearing RADA1 transplants and repeatedly given injections of B6 serum, tumor cells escaped immune destruction despite a lack of modulation. Thus modulation of TL antigenicity on tumor cells in vivo, but not tumor escape, required cell-bound C3.

Animals↗
PubMed1978

In vivo modulation of thymus-leukemia antigens on mouse leukemia cells and thymocytes: retention of modulating antibody on the cell surface.

Inoculation of RADA1, ASL1, and ERLD murine leukemia cells into the peritoneal cavities of (C57BL/6J x A/TL--)F1 mice hyperimmunized against thymus-leukemia (TL) cell-surface antigens rendered most cells insensitive to lysis in vitro by guinea pig complement even in the presence of TL antiserum. Thymocytes of A/J mice were similarly modulated by passive injection of TL antiserum. In all cases, retention of some modulating antibody on the surfaces of most cells modulated in vivo for 1--27 days was indicated by: 1) acquisition of sensitivity of modulated cells to lysis by absorbed rabbit complement; 2) positive immunofluorescence reactions for mouse IgG on the surfaces of modulated cells; and 3) release of cytolytically active TL antibody from cells into the circulation of unimmunized mice following transfer of modulated cells. Reversal of modulation of RADA1 cells was complete in some experiments within 24 hours after transfer to unimmunized mice, by which time all indications of cell-bound TL antibody were lost. These results indicate that even long-term modulation of TL antigenicity in vivo does not result in a complete loss of modulating antibody (presumably attached to TL antigens) from the cell surface.

Animals↗
PubMed1977

Application of freeze-drying intact cells to studies of murine oncornavirus morphogenesis.

Using a method for freeze-drying intact cells, uninfected and murine leukemia virus (MuLV)-infected JLSV9 cell surfaces, as well as murine mammary tumor virus (MuMTV)-infected cell surfaces, were examined by electron microscopy. The 10-nm knobs of MuLV and the 5-nm spikes of MuMTV were clearly revealed on the surfaces of budding viruses and were also found dispersed over the cell surface. The MuLV knobs are randomly arranged on the virus surface, whereas the MuMTV spikes are much more ordered. Because freeze-fractured budding viral envelopes are devoid of intramembranous particles, the observed surface particles do not appear to be merely accentuated intramembranous particles. This technique should permit further analysis of the morphogenesis of viral envelopes without the need for externally applied labels.

Cell Line↗
PubMed1974

Antigenic modulation in vitro. I. Fate of thymus-leukemia (TL) antigen-antibody complexes following modulation of TL antigenicity from the surfaces of mouse leukemia cells and thymocytes.

The modulation or loss of thymus-leukemia (TL) antigenicity from the surfaces of mouse RADA1 leukemia cells and normal thymocytes during incubation with TL antibody in vitro at 37 degrees C was investigated by cytotoxicity, immunofluorescence, and immunoelectron microscopy. The fate of bivalent and monovalent antibody during modulation was visualized by fluorescence microscopy. Considerable antibody remained bound to the cell surface after modulation, bivalent antibody being displaced topographically into "patches" and "caps" while monovalent antibody was only slightly aggregated on the cell surface. Some antibody was internalized, presumably by pinocytosis, and was sequestered into the Golgi region of the cell. Capping usually occurred over the pole of the cell opposite from the Golgi region, which may explain the lack of extensive pinocytosis of modulating bivalent antibody. Since modulation with monovalent antibody occurs without patch or cap formation, gross topographical redistribution of TL antigen-antibody complexes is not required for modulation, although more subtle displacement of these complexes may be involved. Modulation was demonstrable by cytotoxicity with guinea pig C' but not with absorbed rabbit C', indicating that modulated TL antigens remain bound to the cell surface. A heat-labile factor in TL antiserum and in mouse serum in general is responsible for "blocking" the cytolytic interaction of guinea pig C' with modulated TL antigen-antibody complexes.

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