Initiation of noninvasive surveillance for allograft rejection in heart transplant patients > 1 year after transplant.

BACKGROUND: Gene expression profiling (GEP) and donor-derived, cell-free DNA (dd-cfDNA) measurement are alternative methods to endomyocardial biopsy (EMB) to monitor for rejection following heart transplantation. We aim to describe our use of GEP and dd-cfDNA in heart transplant recipients > 1-year post-transplantation. METHODS: This is a single-center, retrospective study in post-transplant recipients. For patients who were > 1-year post-transplantation and deemed to be at elevated clinical risk for rejection, we collected both GEP and dd-cfDNA every 3 months. Baseline characteristics including GEP, dd-cfDNA levels, rejection episodes, and number of biopsies were obtained. RESULTS: Since July 2019, there were 18 patients being followed with GEP and dd-cfDNA who were > 1-year post-transplantation. Nine EMBs had been performed in seven patients due to as follows; three due to elevated GEP ({greater than or equal to} 34), one due to elevated dd-cfDNA ({greater than or equal to} .20%), two due to elevations of both GEP and dd-cfDNA, two due to clinical rejection and one to follow up a post rejection episode. One of the two biopsies due to elevations of both GEP and dd-cfDNA showed acute cellular rejection grade 2R. None of the biopsies due to either an elevation in the GEP or dd-cfDNA revealed any significant rejection. CONCLUSION: In this study, the use of both GEP and dd-cfDNA led to an increased number of EMB in patients > 1-year post-transplantation. Further studies are needed to validate these findings and evaluate long-term consequences of these diagnostic tests in this population.

The role of genetic factors in the immunomodulating effect of thymosin.

The possible role of hypothetical genetic factors involved in the immunomodulating effect of thymosin fraction 7 (T7) was investigated. The model system was the in vitro immunization of murine spleen cell cultures with sheep red blood cells (SRBC), and the generation of antigen specific B cells in T7 treated cultures was compared to that of control values. It was found that T7 treatment enhanced the plaque forming cell (PFC) response of BALB/c spleen cells, while it proved to be suppressive in CBA cultures. Moreover, the T7 treatment of athymic BALB/c nude spleen cells resulted in a marked PFC response to SRBC, while a similar treatment of CBA nude cultures was ineffective in the same assay. The role of possible genetic factors was further confirmed using H-2 congenic and recombinant mouse strains on the C3H and B10 background. T7 elevated the PFC values in all B10 strains tested, and was suppressive in the case of C3H strains. It seems that the outcome of T7 treatment of murine target cells is determined by the genetic background and is independent of the H-2 haplotype.

Alterations of the connective tissue in nude mice.

The epiphyseal cartilage of nude mice was studied by light and electron microscopy. The resting and maturation zones become narrow and mineralization of the ground substance starts already in the zone of proliferation. Electron microscopy reveals signs of degeneration in the chondrocytes of this latter zone. An increased osteoclast activity can be observed in the metaphysis. The alterations may be due to a decrease in T-cell-mediated immunoreactivity of nude mice, as well as to an increased production of the osteoclast-activating factor, which might be attributed, among other things, to the B lymphocytes or macrophages.

Resynthesis of trypsinized sheep red blood cell receptors on human lymphocytes: comparison of the effects of immunopotentiators of biological and synthetic origin in vitro.

Five immunostimulants--thymosin, dialyzable leukocyte extracts containing transfer factor (DLE), isoprinosine, BM 12 531 (azimexon), and levamisole--were compared separately and in various combinations for their ability to increase the binding of sheep erythrocytes by trypsinized human peripheral blood lymphocytes in vitro. Levamisole produced the greatest enhancement when used alone, DLE produced a smaller increase, and isoprinosine, thymosin, and BM 12 531 were less effective. When combining two of these agents, the greatest increase was seen when one of the components was thymosin and the other either DLE, isoprinosine, or BM 12 531. These results indicate possible synergistic mechanisms and the possible advantage of combined therapeutic use of selected combinations of immunostimulants. In the majority of the combinations, however, inhibition rather than stimulation of rosette formation was observed.

Detection of thymosin 5 in calf and mouse thymus and in nude mouse dysgenetic thymus.

Thymosin 5 was traced in calf and mouse thymuses by fluorochrome-labelled rabbit anti-calf thymosin. The presence of thymosin 5 or its individual components was found 1. in groups of cortical epithelial cells in calf thymuses and in single cortical epithelial cells in mouse thymuses. 2. In some marginal (blastema) cells of the thymus cortex of calves and 14-day-old mice. 3. In perivascular epithelial cells of the calf thymus. 4. In occasional medullary epithelial cells of the calf and mouse thymus. In all cases there was a marked alternation of entirely negative and positive cell-containing thymic lobuli. In 4 of 13 cases comparatively strong positivity was found in tightyly arranged epithelial cells in an individual acinus in the dysgenetic thymus of nude mice, the positive cases being concentrated among the youngest mice studied.

The effect of continuous human lymphokine treatment on skin graft rejection in mice.

Continuous intraperitoneal treatment with human lymphokines produced by Con-A stimulated peripheral human lymphocytes caused the acceleration of skin graft rejection in mice.

Studies on cartilage formation. XX. Histochemical investigation of some enzymes of glycogen metabolsim in regenerative articular surfaces.

In 28 dogs the distal articular cartilage of the femur was removed and the regenerating articular surface on the 70th postoperative day was studied histochemically for hexokinase, glucose-6-phosphatase, phosphohexose-isomerase, fructose-1, 6-diphosphatase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, lactate dehydrogenase isoenzymes, phosphoglucomutase, phosphorylase, glycogen synthetase, UDP--glucose dehydrogenase, and UDP-glucuronic acid-4-epimerase. The articular surface consisted of fibrous tissue and of cartilage islets. The latter contained cells differentiating into cartilage and young chondrocytes. The glycolytic enzymes reacted positively in the regenerative articular surface. Enzyme activities were higher in the cells (particularly the chondroblasts and young chondrocytes) of the cartilage islets than in the connective tissue. In the cells differentiations into cartilage, beside the LDH isoenzymes characteristic of glycolysis, a significant LDH1 and LDH2 activity was observed. At the same site the presence of fructose-1, 6-diphosphatase-activity could be assumed, but there was no glucose-6-phosphatase activity. Glycogen synthesis proceeded in the cells of the cartilage islets and UDP-glucuronic acid-4-epimerase activity was observed in the differentiated cells. UDP-glucose dehydrogenase activity was positive in every section of the articular surface.

Connective tissue alterations following neonatal thymectomy. VI. Calcium histochemical, growth-dynamical and thermoanalytical investigations on bone tissue of thymectomized rats.

Thymectomy was performed in newborn rats and the changes occurring in the epiphyseal cartilage and bone were investigated by Ca histochemical and thermoanalytical methods, one, two and six weeks following operation. Formation of Ca complexes was slowed down in the epiphyseal cartilage and the rate of growth decreased. At the same time the inorganic substance content decreased considerably in the bone tissue of operated rats as compared to the controls.

Studies on cartilage formation. XVI. Chemical and histochemical assay of lipids in the regenerating articular cartilage.

The articular surface of the distal part of the femur was removed operatively in dogs, and the regenerating articular surface and the GTC were investigated at different stages from the 7th to the 70th postoperative days. During this period cartilage islets arose in the GTAS, while the GTC transformed to connective tissue. At 7 days the lipid content of the tissue was markedly higher than at the other stages studied. Lipids, predominantly triglycerides, were present in extracellular form as well. From the 20th to the 70th day the PL fraction became predominant and, in addition to the pre-existing lecithin, relatively large quantities of lysolecithin, sphingomyelin, phosphatidyl-ethanolamine, phosphatidyl-serine and phosphatidyl-inositol could be gradually demonstrated. Differences were noted in the time of appearance and binding of PLs between the two types of granulation tissue. As time proceeded, the proportion of saturated fatty acids decreased in favour of unsaturated ones. At 70 days, the GTAS contained fatty acids up to C18. About 50% of the fatty acids consisted of C16:1, C18:2 and C18:1. At the same stage, in the GTC C16:1, C18:1 and C20:1 were present in larger amounts. Of the free fatty acids C16:1, C16 and C18 were in predominance in the GTAS and the proportion of fatty acids having more then one double bonds increased with time. In the GTC C16 and C18:1 were in great majority. According to histochemical evidence, the tissues did not contain extracellular lipids from the 20th postoperative day. In the cells, the presence of glycerides, PLs, lipoproteins and cholesterol was demonstrated. In addition, in cartilage precursors of more advanced maturity, a considerable fatty acid positivity was noted.