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The complete Dane particle consists of two serologically and morphologically different components: Core (HBc) and Surface (HBs). HBc is located almost exclusively in the liver cell nucleus and can be demonstrated by immunofluorescence and electron microscopy, but not by light microscopy. HBs is located exclusively in the cytoplasm and can be demonstrated by immunofluorescence (IF) and, if present in excess, by electron an light microscopy (as ground-glass hepatocytes). The combined analysis with IF, electron and light microscopy of biopsy specimens taken from patients with different forms of hepatitis with and without immunosuppresive therapy allows recognition of at least four different reaction patterns: 1. Immunosuppression type (= HBc-predominance type), 2. Elimination type, 3. Aggressive type (= HBc+s equivalence type, 4. Carrier type (= HBs-predominance type). The patterns of HB-Antigen components are of prognostic value as to the clinical course of hepatitis. These findings strongly suggest that immune responsiveness determins the reaction pattern, the key mechanism being immune elimination of affected cells. In addition, these findings stress the role of the immune system in regard to the variability to the clinical course of hepatitis B, and shed light on morphological correlations.

A series of 67 liver biopsies (20 kidney transplant recipients and 47 outpatients with hepatitis) was investigated for the presence of hepatitis B antigen core (HBc) and surface (HBs) components by immunofluorescence and electron microscopy. The variable appearance of the core in liver cell nuclei and of the surface in the cytoplasm allowed the recognition of expression patterns which, together with histologic parameters, could be integrated into four reaction types of diagnostic and prognostic implications: Type I (Elimination Type). No components or only occasional expression of HBc; histologically, classic lobular hepatitis; clinically, acute, self-limited viral hepatitis. Type II (HBc Predominance, or Immunosuppression Type). Abundant core expression in each liver cell nucleus and moderate appearance of HBs; histologically, nonaggressive inflammation (nonspecific reactive or portal hepatitis); clinically, mild, chronic, persistent hepatitis in transplant patients. Type III (HBs Predominance, or Nonaggressive Type). Prominent HBs expression largely in the absence of HBc; histologically, nonaggressive inflammation (nonspecific reactive and portal hepatitis) or normal liver tissue, together with ground-glass hepatocytes in light microscopy, as a correlate of HBs-containing hepatocytes; clinically, hepatitis B antigen carrier, or chronic persistent hepatitis. Type IV (HBc+s Equivalence, or Aggressive Type). Spotty expression of both components, especially of core; histologically, periportal hepatitis; clinically, mainly corresponds to chronic aggressive hepatitis and to acute hepatitis with possible transition to chronicity. As a unifying concept for these types, it is suggested that immune responsiveness determines the reaction pattern, the key mechanism being immune elimination of affected cells. Between efficient elimination (type I) and effective immunosuppression (type II), a graded elimination insufficiency is found in chronic forms (types III and IV), explaining the persistence and probably also the aggressiveness of hepatitis B virus infection.

The autopsy and electron microscopic findings in a pair of brothers with congenital dyserythropoietic anemia (CDA) are presented. In both patients autopsy revealed severe secondary hemochromatosis, including cirrhosis of the liver and fatal heart involvement. According to current ultrastructural criteria, a mixture of CDA type I (interchromatin bridges, wide euchromatin-cytoplasmic connections) and of type II (marginal cisternae, nuclear protrusions, multinuclearity, karyorrhexis) was found in erythroblasts of one patient. In the second patient electron microscopy of bone marrow stored in formalin for several years allowed the diagnosis of CDA with marginal cisternae in retrospect. These findings illustrate the usefulness of electron microscopy for the diagnosis of CDA in unsolved cases of chronic ineffective erythropoiesis, even from formalin fixed material. For subtyping CDA into type I and II, however, other than morphological parameters should be used for definition. In the clinical management splenectomy and a drastic phlebotomy programme have been found favourable.

Viral hepatitis, proven by biopsy in 44 patients known to be drug addicts or confirmed drug takers had serial clinical, biochemical and (half of them) biopsy studies between 1971 and 1974. At the time of the first biopsy the period of addicition averaged 28.8 months. 30 of the 44 patients had had jaundice. At the time of the last biopsy, 20 of the 44 had chronic persisting and three had chronic active hepatitis, i.e. more than half had a chronic form. A further 12 patients had "hippie" hepatitis, a special form of acute viral hepatitis with piecemeal necrosis, histological evidence of possible change to a chronic state. There was no case of complete healing during the period of observation. The high rate of chronic hepatitis is thought to be due to partially insufficient immune response. The clinical and even biochemical course in most of the patients was remarkably mild. Severe clinical forms are rare and were not observed at all in the described group. It would therefore, seem that the prognosis is generally good, in contrast to chronic hepatitis in non-addicts.

Immunofluorescent and electron microscopic methods allow the localization of hepatitis virus B-components at the cytologic and histologic level. The acute and chronic forms of viral hepatitis are re-evaluated in the light of these new findings. In HB-Ag-positive hepatitis four types of correlation between the expression pattern of HG-Ag components and different forms of hepatitis are recognized which are of diagnostic and prognostic relevance (elimination type, immunosuppression type, aggression type, and carrier type). The correlation between antigen expression, persistence of infection and type of inflammation seems to reflect the specific immune state towards the hepatitis B virus.

Antibody-bearing cells of spleen and lymph node of the mouse and rabbit detected by rosette formation with the antigenic red blood cells were collected by micropipet and studied by electron microscopy. More than 300 such cells were examined. In the lymph nodes, rosette-forming cells were all in the lymphocytic and plasmacytic categories. In cells of the mouse spleen, macrophages were also found among the RFC, especially in the later days after immunization. The great majority of the RFC, 70-100%, were of the lymphocytic category. These included small, medium, and large lymphocytes with fine gradations of differentiation, and blast forms with little heterochromatin. The endoplasmic reticulum of these cells occurred in short, very narrow pieces, usually in contact with a mitochondrion. The cells of the plasmacytic category also showed fine gradations from plasmablasts to typical mature plasma cells. Plaque-forming cells of mouse and rabbit were also collected by micropipet. Of 162 such cells, fine gradations were also found throughout the lymphocytic and plasmacytic categories, but in this case the great majority were in the plasmacytic group, and more plasma cells showed amorphous nuclear chromatin. Among antibody-forming cells detected by both reactions, some of the more highly differentiated large lymphocytes contained ER which differed from that in the other large lymphocytes in that the channels were slightly and variably distended, with deposition of some precipitate, and with some tendency to a more nearly parallel orientation of the few channels seen. These were considered transitional cells. Of 10 RFC found in mitosis, all were in the lymphocytic category, in various stages of differentiation, the most advanced of which (in 2 of the 10 cells) was that of the transitional lymphocyte described here. Cells producing plaques facilitated by antisera vs. IgG of the mouse or rabbit (7S) showed the same distribution between cell categories and the same fine gradations as the direct (19S) PFC. Cells producing rosettes which were resistant to lysis in the presence of complement, and were thus presumably producing 7S antibody, showed a distribution similar to that found generally with rosette-forming cells, approximately 80-90% in the lymphocytic category.

A study of the kinetics of antibody-producing cells has been carried out by the use of rosette formation for detection of individual antibody-producing cells, and labeling with tritiated thymidine, in cells obtained from mouse spleens at intervals after injection of SRBC. Following a primary injection of the antigen, the number of RFC per million cells was found to increase to a peak at 5 days, then, after a decrease, to a second peak at about the 10th day. The curve of tritium labeling of RFC was also biphasic, with peaks on the 3rd and 7th day. The second increase in rosette-forming cells could be shown to involve, especially between the 7th and 9th day, a second increase in lymphoid cell RFC and, among these, 7S antibody-producing cells. When the population examined was restricted to large lymphocytes, two peaks of RFC per million cells and two peaks of labeling were again found. In this case, however, the peaks of RFC and of labeling were reached on the same day in each instance, rather than with the 2 day difference found in the entire spleen cell suspension or the entire lymphoid cell population. Electron microscopic examination of labeled rosette-forming cells showed these to be largely lymphocytes, but to include rather well differentiated plasmablasts as well. No macrophages were found among labeled RFC in the primary response. A substantial number of labeled lymphocytes were found in close contiguity with rosette-forming macrophages. The percentage of labeling in such lymphocytes was as high, on the respective days, as the percentage of labeled cells among the RFC of the entire suspension.

Mice injected with sheep RBC and then, 4 days later with thymidine-(3)H, were sacrificed on the day of thymidine-(3)H injection or 1 or 2 days later. Hemolytic antibody plaque preparations were made of cells from the draining lymph nodes by a thin-plating procedure permitting collection of isolated PFC for electron microscopic examination and radioautography. Of cells obtained on the day of thymidine-(3)H injections, 65% of the labeled PFC were in the lymphocytic category, in comparison with 13% found previously in the entire population of such cells. The remaining 35% were plasmablasts in early stages of differentiation. Cells obtained 1 day after the thymidine-(3)H injections showed a shift to a majority of labeled cells in the plasmacytic category. Also, the plasmablasts were substantially more differentiated than those of the previous day, and some mature plasma cells were now seen. The labeled PFC obtained on day 2 gave no indication of further differentiation. Cells of rabbit lymph nodes labeled in vitro with thymidine-(3)H showed a range of labeled PFC. The majority were in the plasmacytic category, including some mature plasma cells. The data from the experiments with in vivo labeling suggest a direct differentiation from antibody-synthesizing lymphocytes to plasma cells. Further, the in vivo experiments indicated that differentiation from nascent lymphocyte to plasma cell could be essentially completed within 1 day.

The ultrastructure of binding sites in rosette-forming cells of mice after immunization with sheep red cells was studied by means of scanning and transmission electron microscopy. It was found that the red cells were bound to the lymphocyte surface in circumscribed, immunoglobulin-containing areas, consistent with a spotlike or patchy distribution of antigen-binding immunoglobulin receptors. In these contact areas the cell membranes formed a gap of 80 A (range 75-90 A) which exhibited electron-opaque bridges at high magnification. These results are discussed in the light of the recent recognition of the formation of immunoglobulin spots on the lymphocyte surface after antigen contact. Morphological details suggest that the same mechanism is operating in rosette formation, possibly including the movement of the contact areas on the lymphocyte membrane.