The object of this thesis was to study the role of thymic humoral factors in the maturation of rat lymphoid cells. The response, in vitro, of lymphoid cells to PHA, measured by the incorporation of tritiated thymidine, was used as a measure of thymic function. Neonatal thymectomy led to a persistent lymphopenia and a drastically reduced response of rat whole blood and spleen cells to PHA. Partial restoration of the lymphocyte count and PHA response occurred in thymectomized rats following the transplantation of two syngeneic thymuses. Analysis of the PHA response and lymphocyte count in individual whole blood samples suggested that the response to PHA was a good measure of the peripheral blood T cell population. Addition of serum to the medium was not necessary in order to obtain a satisfactory response to PHA provided that erythrocytes were present. No difference was found between the ability of pooled intact rat and pooled thymectomized rat serum to depress, or increase, tritiated thymidine incorporation in cultures of rat blood or spleen cells responding to PHA. Incubation of unfractionated lymphoid cells with crude cell-free saline extracts of rat thymus was not found to increase the responsiveness of the cells to PHA. When the extract was present throughout the culture decreased isotope incorporation occurred. When the extract was removed from the cells after a preculture and before the addition of PHA the isotope incorporated in response to PHA was either slightly increased or decreased. Incubation of unfractionated spleen, bone marrow and thymus cells with cell-free medium obtained from three-day and six-day thymus organ cultures did not load to increased responsiveness to PHA. Also, 40 injections of thymus organ culture medium given to each of 12 neonatally thymectomized rats over an eight week period did not increase the whole blood response to PHA.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649727 |
| Date | January 1978 |
| Creators | Drewitt, D. J. N. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/17161 |
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