I. Immunosurveillance and tumorigenesis in 1. BALB/c mice. Early reactive state in the jejunum disseminated lymphoid tissue.

Using functional ultrastructure we established the physiology of the cellular immune response in the BALB/c mouse jejunum disseminated lymphoid tissue (JDLT) before and after sequential stimulations with E. coli endotoxin (ECE) (the preceding article in this journal). The functional ultrastructure was established also in this series of BALB/c mice injected i.p. initially with 0.5 ml of mineral oil and then weekly with 5 ng of ECE (EOA). The present series of mice had a pathological immune response and, it is known that they will in time produce plasmacytomas. Differences between the physiologic and pathologic immune responses during the first month of tumorigenesis, are: 1. The T-lymphocyte response was found to be strong but disorganized; 2. As judged from the T:B ratios, the B-lymphocyte response was found to be very strong, late after the first, early after the second, and late after the fourth injections with ECE, in this EOA model of stimulation. 3. The macrophage cellular response during the EOA stimulation was found to be slightly weaker than that seen in the series of mice stimulated with ECE alone. At the time of this study, the differences found between the physiologic and pathologic immune responses in the JDLT are not conclusive and they do not elucidate either the mechanisms of tumorigenesis or the role of the immunocompetent cells.