This study examines the possible mechanisms by which radiation and the bacterial toxin, Tetanus toxoid (TT), suppress the murine splenic mononuclear cell (SMNC) response to mitogen. This study demonstrates that the lymphocyte proliferation response of SMNC to the mitogenic lectin PHA can be suppressed by TT in a dose-dependant manner in vitro, without affecting the viability of the cells, in the anti-proliferative concentrations used (0.5-5 $\mu$g/ml). SMNC pre-incubated with TT could suppress the pHA blastogenic response of fresh autologous cells during co-incubation suggestion the involvement of activated suppressor cells. Flow cytometric analysis demonstrated that TT does not produce an alteration in the cellular balance, indicating that the suppression would appear to be dependant upon a change in T cell function. TT down-regulated the expression of class II MHC antigens on antigen-presenting cells which may represent an inappropriate costimulatory signal required for T cell activation. Whole body irradiation has been reported to induce active immune suppression. In the present study, ionizing radiation (0-700 cGy) produced decreased spleen cellularity and decreased ability of surviving SMNC to respond to mitogen. There was no evidence, however, to indicate that irradiation (100 cGy) activated suppressor cells during the first 7 days post-irradiation. Similarly, radiation did not seem to interact with TT to increase the amount of TT-induced suppression. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/6528 |
| Date | January 1994 |
| Creators | Harrington, Noel P. |
| Contributors | Ross, William, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 180 p. |
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