Studies on the Mitotic Responsiveness of “T” Cells After Stimulation with Contact Sensitizing Agents

Abstract

Oxazolone, in common with other contact sensitizing agents such as picryl chloride, induces in the lymph nodes draining its site of application a complex series of reactive changes (9, 15). These changes include during the first few days of the response mitotic activation of T (thymus derived) cells (2). At the time of this activation the histopathological changes have been described as paracortical hyperplasia (2, 10). This is appropriate as the paracortical or interfollicular cortical regions have been said to be thymus dependent (11, 12). By this is meant that, in organisms in which for various reasons the thymic influence has been lacking during the ontogeny of the lymphoid system, there is a quantitative deficiency of cells in these locations. The same region includes those organs known as postcapillary venules through the walls of which lymphocytes escape from the blood stream into the body of the lymph node thus enacting the defining characteristic of a lymphocyte — its capacity to recirculate (5). It should be remarked that both T and B (bursa-equivalent derived) lymphocytes have this faculty to recirculate (7, 8). A difference between the two cells arises after emergence from the blood stream in that whereas the model behaviour of the B cell in unstimulated nodes is to move into the outer follicular regions of the cortex, the T cells tend to remain in the deeper regions (4).