Using the mixed lymphocyte reaction (MLR) as a correlate of cell-mediated immunity, an examination was made of positive and negative blastogenic immunoregulation by syngeneic peritoneal macrophages (M<sub>Φ</sub>) and splenic T cells from tumor-bearing mice (TBM). As analysis of T cell proliferative response progressed an intricate pattern of immunoregulatory checks and balances unfolded involving both M<sub>Φ</sub> and TBM cells.
In their capacity as regulators, M<sub>Φ</sub> acted, not only to enhance MLR reactivity, but to inhibit it. Results indicated that: i) M<sub>Φ</sub> regulation was a concentration dependent phenomena -- high concentrations of M<sub>Φ</sub> (or their supernatants) inhibited MLR reactivity, while low doses enhanced MLR reactivity; ii) inhibition occurred via a non-toxic, heat stable, nondialyzable (and therefore non-thymidine) factor; iii) enhancement occurred via a heat labile nondialyzable factor.
Since normal M<sub>Φ</sub> possessed a factor which, in high concentrations, inhibited T cell blastogenesis, tests were run to determine if the MLR hyporeactivity of T cells from TBM could be attributed to a unique tumor-induced inhibitory M<sub>Φ</sub>. Contrary to expectations, TBM M<sub>Φ</sub> supernatants, when compared to their normal counterparts on a volume-to-volume basis. showed an increased (not decreased) ability to enhance MLR reactivity.
In light of results showing TBM M<sub>Φ</sub> enhancement of MLR reactivity, T cell hyporeactivity in TBM was explained after observation of the following dual regulatory mechanism of suppression: i) on a purely quantitative basis, the high in vivo concentration of M<sub>Φ</sub> in spleens of TBM inhibits spleen cell response to alloantigen; ii) there also exists a population of mildly nylon wool adherent tumor-induced splenic T cells which elaborate a soluble factor capable of overriding any M<sub>Φ</sub> enhancing effect.
In their capacity as regulators, tumor-induced splenic T-cells act, both to enhance and inhibit MLR reactivity. Whereas M<sub>Φ</sub> regulation is concentration dependent, in the case of the T cell regulator, regulation is based, not upon the relative concentration of the regulator cell, but upon the level of responder cell activity, i.e. M<sub>Φ</sub>-depleted MLR cultures (showing minimal proliferation) were enhanced by regulator TEM T cell addition, while M<sub>Φ</sub> augmented MLR cultures or PHA stimulated cultures (with a high rate of blastogenesis) were inhibited by the same concentration of TBM regulator cells.
Centering around more stringent biophysical and biochemical characterization of M<sub>Φ</sub> supernatants, the latest work has resulted in the biochemical separation of M<sub>Φ</sub> supernatants into inhibitor and enhancing components. Using anion exchange chromotography and slab gel electrophoresis, inhibitor and enhancing factors have been separated by charge. Treatment of M<sub>Φ</sub> with indomethacin did not abrogate release of inhibitor factor, suggesting that it was not prostaglandin. Enhancing factor, obtained from M<sub>Φ</sub> sonicates as well as supernatants, could be distinguished from lymphocyte activating factor by its inability to induce a thymocyte PHA response.
Thus, analysis of regulation in the cell-mediated immune system has resulted in the elucidation of a most elaborate scheme of immunoregulation involving both M<sub>Φ</sub> and T cells. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/39002 |
| Date | 28 July 2010 |
| Creators | Connolly, Kevin Michael |
| Contributors | Microbiology, Elgert, Klaus D., Bates, Robert C., Krieg, Noel R., Conroy, James M., Schurig, Gerhardt G. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | xiv, 197 pages, 3 unnumbered leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 05543863, LD5655.V856_1979.C665.pdf |
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