Detection of precursor Th cells in mesenteric lymph nodes after oral immunization with protein antigen and cholera toxin

We have characterized the earliest antigen-specific Th cells in murine mesenteric lymph nodes (MLN), following oral immunization with the hen egg lysozyme (HEL) as antigen and cholera toxin (CT) as adjuvant. We did this by analyzing in vitro proliferation and cytokine production in response to HEL by the MLN T cells. MLN cells taken 5 days after a single oral immunization with HEL and CT provided the earliest source of proliferating HEL-specific T cells. This proliferation was completely inhibited by anti-IL-2, but not inhibited by anti-IL-4 antibody. IL-2 protein was detected in culture supernatants but not IL- 4 using ELISA or bioassays. IL-4 mRNA was not found in responding cells using RT-PCR. Some of the day 5 MLN cultures produced IFN-gamma in response to HEL, but isolated T cells from the same MLN did not. Exogenous IL-4 alone did not stimulate day 5 MLN T cells, but IL-4 did synergize with HEL to induce a large proliferative response. The data indicate that the HEL-specific CD4 T cell pool in MLN 5 days after oral immunization is composed of undifferentiated precursor Th cells. These cells have the potential for IL-2 production and IL-4R expression upon re-stimulation in vitro.      

CT of the pulmonary nodule: a cooperative study

To evaluate the role of computed tomography (CT) in the investigation of pulmonary nodules, a special reference phantom that enabled CT densitometric measurements independent of variations between scanners and patients was used in ten institutions. A total of 384 nodules not considered calcified by conventional methods were examined; 118 (31%) proved to be benign, and in 65 of these (55%), unsuspected calcification was demonstrated. In 28 of the 65, definite calcification could be identified on thin-section CT scans by simple inspection of the scans at narrow windows. In the remaining 37, presence of calcification could not be clearly established without comparison with the reference CT number from the calibration phantom. CT was most effective in establishing the benignancy of nodules 3 cm or less in diameter and those with discrete or smooth margins. CT rarely yields a confident diagnosis of benign disease in larger nodules and in those with irregular or spiculated borders. After review of prior spot radiographs, low kilovolt peak spot radiographs, and conventional tomograms, the authors conclude that thin-section CT aided by a reference phantom in equivocal cases should be an integral part of the diagnostic approach to the pulmonary nodule.