The in situ cellular immune response in BALB/c mice jejunum disseminated lymphoid tissue after stimulations with E. coli endotoxin.

The feasibility of the functional ultrastructure, a term used to describe the in situ immunocumpetent cell topography, B-cell transformation, multiplication and cell-to-cell interactions, was only recently made possible (Toma et al. 1977a; Toma and Retief 1978). The functional ultrastructure of the BALB/c mice jejunum disseminated lymphoid tissue (JDLT) before and after four i.p. sequential stimulations with 5 ng E. coli endoxin (ECE) each revealed the following results: 1. The in vitro T-cell response was found to be by recruitment and not by the in situ cell division. T-lymphocyte recirculation in the thymus may be the answer to the question "Where does the clonal proliferation occur?" 2. Two T-cellular immune responses have been identified, one occurring early during the stimulation (1st and 2nd stimulations) and the other occurring late (after the 4th stimulation with ECE). It was thought that the first T-cell response represented the helper type of the immune response, whereas the second would represent the suppressor T-cell response. 3. The B-cell response, as judged from the percentage of plasma cells (PC) generated, was strong in the T-PC islands but no patterns of its generation could be established. 4. The curious topography of the immunocompetent cells inside the T-PC islands in the Lieberkühn crypts was found and their origin discussed. We aimed to establish the physiology of the cellular immune response in JDLT and to use it as a normal comparative model. It will be compared with the pathology of immune response in this part of BALB/c mouse gut established by immunosurveillance and tumorigenesis in artificially induced plasmacytomas with mineral oil (the following article).