Dendritic cells, in contrast to B lymphocytes, must be able to efficiently internalize a diverse array of antigens for processing and loading onto major histocompatibility complex (MHC) class II molecules. Here we characterize the mannose receptor pathway in dendritic cells and show that mannose receptor-mediated uptake of antigens results in a approximately 100-fold more efficient presentation to T cells, as compared to antigens internalized via fluid phase. Immunocytochemistry as well as subcellular fractionation revealed the localization of the mannose receptor and MHC class II molecules in distinct subcellular compartments. The mannose receptor thus functions in rapid internalization and concentration of a variety of glycosylated antigens that become available for processing and presentation. This may contribute to the unique capacity of dendritic cells to generate primary T cell responses against infectious agents.

SUMMARYAll of our cases of abnormal pulmonary venous connections collected to the middle of 1965 and verified at surgery or autopsy have been reviewed by means of diagrams and tabulations, using a specially devised code to facilitate the survey. The material consisted of 52 autopsy cases (half of them obtained after surgery) and the cases of 72 patients who survived operation. The postmortem group was much younger than the surgical group and differed also from the latter by showing male preponderance as well as relatively many instances of total abnormal pulmonary venous connection and frequently associated cardiac anomalies.Partial anomalous connection of right pulmonary veins was 10 times more frequent than that of the left pulmonary veins. This was caused by (1) the frequent drainage of some of the right pulmonary veins into the junctional area between right atrium and superior vena cava in the presence of normal left pulmonary veins, and (2) the complete absence of isolated left pulmonary venous connection to the right atrium. Abnormal connection of solitary pulmonary veins was always effected to the most proximal venous structure among the four possible ones which are derived from the main embryonic channels (superior vena cava and inferior vena cava on the right side, and left superior vena cava and coronary sinus on the left side). Common pulmonary veins from one lung also drained in accordance with this proximity rule, if this may be taken to apply also to the drainage of right pulmonary veins into the right atrium. The one exception in our material was the drainage of all right pulmonary veins into the portal venous system. Total abnormal pulmonary venous connection may be found with all structures mentioned, but most frequently with the left superior vena cava, or coronary sinus, or both, usually by way of a common pulmonary vein. In a few cases however, drainage into different sites, all of them abnormal, did occur. Then again the proximity rule seemed to apply.A tentative embryological explanation is given for the patterns described.Additional Indexing Words:Congenital heart disease Atrial septal defect Anomalies of venae cavae IN TWO previous publications some of our cases of anomalous pulmonary venous drainage were described. The first paper' dealt with the clinical-in particular the radiological-diagnosis and the second2 with our From the Afdeling voor Cardiologie, Academisch

These data indicate that unstimulated milky spots in the human greater omentum are to a great extent just a preformed specific accumulation of primarily macrophages within the stroma of the greater omentum, and therefore, cannot be regarded as true secondary lymphoid tissue. Milky spots could serve as a gateway for, as well as a provider of peritoneal macrophages when the intra-abdominal status so requires. Finally, the data from this study are compared with the data of other studies of human milky spots and those in animals.

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