Defective B cell clonal regulation and autoantibody production in New Zealand black mice

By using the splenic fragment assay in a KLH-primed host, we have evaluated the clonal anergy model of tolerance in DBA/2 and spontaneously autoimmune NZB mice. Unlike immature B cells from DBA/2 mice (which are tolerized by encounter with TNP-OVA), SIg- B cells from NZB mice respond to TNP-KLH with equal precursor frequency in TNP-OVA-tolerized or control fragments. In additional experiments, SIg- bone marrow or mature spleen cells of DBA/2 or NZB origin were adoptively transferred into irradiated (DBA/2 X NZB) F1 X xid hosts, and host-derived splenic fragments were stimulated in vitro with LPS and growth factors. These experiments revealed a substantial anti-ssDNA precursor frequency in NZB marrow and spleen (2.5 and 5.1, respectively, per 10(7) transferred cells). In DBA/2 SIg- marrow cells, there was an anti-ssDNA precursor frequency of 1.3 to 3.5/10(7) transferred cells; however, anti-ssDNA-producing clones were reduced in fragments derived from recipients of DBA/2 as compared with NZB spleen cells (0.2 to 1.9/10(7) transferred cells). By using a replica plate technique, we evaluated fragments from recipients of DBA/2 SIg- marrow cells or mature spleen cells for anti-TNP reactivity. In fragments derived from recipients of DBA/2 SIg- marrow cells, 92% of anti-TNP-producing fragments also bound ssDNA. In fragments derived from recipients of DBA/2 spleen cells, only 43% of anti-TNP-producing fragments also bound ssDNA. Our findings document that NZB marrow-derived immature B cells abnormally resist tolerance induction, and that clonal anergy/selection operates in directing the B cell repertoire away from autoantibody formation.     

Isolation of a developmentally regulated lectin from chick embryo

A lectin is isolated from the microsomal fraction of chick embryo kidney after initial extraction with 1 M urea and 0.3 M lactose. To exhibit hemagglutination activity, the lectin in the microsomal fraction requires prior activation by solublization with deoxycholate or by treatment with trypsin, chymotrypsin or phospholipase c. The lectin is partially purified by hydrophobic interaction chromatography about 200 fold from the microsomal fraction. The lectin binds strongly to de-sialated embryonic carbohydrates and shows low affinity toward glucosamine, galactosamine and mannosamine, as judged by the inhibition of hemagglutination. Comparison of the lectin activity from kidneys of embryos at different ages shows that the lectin is developmentally regulated.     

Surface structure changes of rat adipocytes during lypolysis stimulated by various lypolysis stimulated by various lypolytic agents

A qualitative and quantitative electron microscopic study was performed on rat adipocytes during stimulation of lipolysis by various agents. Scanning electron microscopy of control cells revealed a spherical cell with a textured glycocalyx surface exhibiting small irregular projections. Globular surface evaginations or protrusions measuring 8-18 μM in diameter were seen on cell hemispheres, and there was an average of one protrusion for every two hemispheres examined. Distribution analysis showed that 60 percent of the hemispheres had no protrusions, and 25, 10, and 5 percent of the hemispheres had one, two or three protrusions, respectively. Thin-section and freeze- fracture electron microscopy of the protrusions showed a small triglyceride droplet surrounded by a thin cytoplasmic rim that was continuous with the main cytoplasmic matrix. The glycocalyx coating and plasma membrane extended from the cell surface onto, and over, the protrusion. Scanning microscopy of cells stimulated by lipolytic agents, including epinephrine, adrenocorticotropic hormone, theophylline, and dibutyryl cyclic AMP, revealed a dose-dependent increase in the number of protrusions per cell hemisphere. Maximal concentrations of lipolytic hormones cuase an average 2.5-fold increase in the number of protrusions per hemisphere without changing the average size of the protrusions. Only 40 percent of the stimulated cell hemispheres exhibited no protrusions; over 15 percent of the cells contained three or more; and a number of the protrusions were multilobulate. Insulin prevented the increase in the number of protrusions and the change in distribution caused by the lipolytic hormones but did not prevent the increase caused by theophylline and dibutryl cyclic AMP. The data suggest that the protrusions are a structural feature of the cell and may be related to the lypolytic pathway. These observations may help explain some of the discrepant biochemical data relating to hormonal stimulation of lipolysis.     

Nature of the transport ATPase-digitalis complex. VI. Purification of and ouabain binding to a highly active cardiac Na+, K+-ATPase

A Na⁺,K⁺-ATPase has been isolated from canine heart with a specific activity as high as 200 μmoles of inorganic phosphate/mg protein/hour. Activity is not due to simple detergent activation since specific ouabain binding (i.e., [Mg⁺⁺,Na⁺,ATP] or [Mg⁺⁺,P_i]-ligand dependent) ranged from 200–450 pmoles/mg protein. Specific ouabain binding activities are up to ten times greater than heretofore reported.     

Effects of nucleotides and Na + on ouabain activation of the phosphatase associated with Na + , K + -ATPase

Ouabain activation of the phosphatase associated with Na⁺,K⁺-ATPase is a time-dependent process which is stimulated by ATP and other nucleotides. Further stimulation by Na⁺ is observed under certain conditions. The stimulatory effect of ATP was found to be due to an increase in the affinity of the enzyme for ouabain. The time required for maximal ouabain activation to be achieved was decreased by ATP and further decreased by ATP + Na⁺.These conditions for maximal activation by ouabain are similar to those required for maximal ouabain binding and suggest that the same ouabain site is responsible for activation of Mg²⁺-dependent phosphatase and for inhibition of Na⁺,K⁺-ATPase and K⁺-phosphatase.     

Cytology of angiosarcoma in effusions

The cytologic and immunocytochemical findings in pleural effusions from three cases of angiosarcoma are presented. In two of the cases, the primary lesion was on the scalp; in the third case, an angiosarcoma of the small intestine developed after radiotherapy for Hodgkin's disease. Single malignant cells and small clusters of cells were seen in cytologic preparations from two cases while only single cells were seen in preparations from one case. The malignant cells had delicate, finely vacuolated cytoplasm with distinct borders. No specific morphologic features were noted. Immunoperoxidase studies revealed binding of Ulex europaeus and reactivity for vimentin in all three cases and expression of Factor VIII-related protein in two of the cases but no expression of epithelial markers. The clinical history and immunoperoxidase studies are necessary to distinguish angiosarcoma from metastatic adenocarcinoma and other malignancies in effusions.