Estrogen-receptor expression and function in thymocytes in relation to gender and age.

The expression of estrogen receptor (ER) in thymocytes was studied in young, middle-aged, and old (2, 12, and 24 months, respectively) female and male C57BL/6J mice. Western immunoblots prepared from the thymocytes of females of all age groups showed the presence of a 67-kD protein band, which has been associated with the apparent MW of denatured ER. Flow cytometry analysis of cells stained with a monoclonal anti-ER antibody (clone 13H2) disclosed ER expression in both females and males of all age groups. In vivo treatment with estradiol (E2) led to an increase in the specific activity of thymic creatine kinase (CK) in the female mice, whereas the male thymocytes responded with an increase in CK activity only on treatment with dihydrotestosterone (DHT). The data show no differences in ER expression between male and females, but the receptor appears not to be functional in males. Interestingly, when estradiol was applied to co-cultures of lymphoid-depleted fetal thymus (FT) explants and bone-marrow cells, or thymocytes, from young and old females, it resulted in increased cellularity of cultures containing cells of the young, and not those of the old. The proportion of CD4/CD8 phenotypes of the developing cells in these cultures was not affected by E2 treatment. These observations provide a new insight into ER expression and function in T-cell development in relation to gender and age.

Treatment of human ulcers by application of macrophages prepared from a blood unit.

Decubital ulcers contribute to morbidity and mortality in elderly patients. Macrophages play a major role in the process of wound healing. We compared the efficacy of local treatment of decubital ulcers in elderly patients using macrophages prepared from a blood unit, vs. conventional treatments. Patients with decubital ulcers (n = 199) hospitalized during one year in a Geriatric Hospital in Israel, were included in the study. The ulcers of 72 patients (average age 82), who provided informed consent, by themselves or by family, were treated by local injection of macrophages prepared from a blood unit in a closed sterile system. The remaining 127 patients (average age 79) were treated conventionally and served as controls. No exclusion criteria were applied. Only a completely healed ulcer was considered a positive outcome of treatment. In the macrophage-treated group 27% (36 out of 131 ulcers) were healed compared to 6% (15 out of 248) in the control group (p < 0.001). There was also a significantly faster healing in the experimental group (p < 0.02). No side effects were noted. We conclude that Macrophages prepared from a blood unit, in cost-effective, closed, sterile system, are significantly more effective than conventional methods for the treatment of ulcers in elderly patients.

Effect of serum amyloid A, HDL-apolipoprotein, on endothelial cell proliferation. Implication of an enigmatic protein to atherosclerosis.

The possible contribution of apo-HDL serum amyloid A (SAA) to the protective effect of HDL against atherosclerosis was studied by evaluating its effect on bovine aortic endothelial cell (BAEC) proliferation. Our results suggest that human SAA, both purified and recombinant, in concentrations relevant to mild acute phase events, significantly inhibit endothelial cell proliferation in a dose-dependent manner (e.g., 50 micrograms/ml causes approximately 88% inhibition; p < 0.001). This inhibition was attenuated by addition of fibroblast growth factor (FGF), which antagonized the SAA-mediated effect. As levels of TNF may be highly elevated during the acute phase response, its effect on BAEC proliferation was evaluated and found, at concentrations of > 1 pg/ml, to be substantially inhibitory Co-incubation of cells with both SAA and TNF was inhibitory, albeit neither additive nor synergistic. FGF antagonized the effect of both proteins. Amyloidic deposit (AA, i.e. SAA 1-76), derived from pathological proteolysis of SAA, practically retains the inhibitory activity (e.g. 50 micrograms/ml causes approximately 66% inhibition; p < 0.001) but apparently lacks the regulatory site towards FGF. In contrast to the above inhibitory effect, synthetic SAA-related peptide corresponding to the sequence 29-33 of SAA enhances BAEC proliferation (50 micrograms/ml causes approximately 64% increase; p < 0.001). The present data, coupled with our previous observations in which SAA was found to induce endothelial PGI2 formation and to inhibit overproduction of PGI2 by TNF and LPS as well as platelet aggregation, may suggest that SAA contributes to the protective effect of HDL against atherosclerosis. This, by means of its modulatory effect on endothelial cell and platelet activation, primarily in the presence of other regulatory proteins. SAA-derived peptides may, potentially, be used as therapeutic agents in the treatment of atherosclerosis and cardiovascular diseases.

Early lesions of the articular surface in a strain of mice with very high incidence of spontaneous osteoarthritic-like lesions.

Our study was designed to see if the lesions of the articular surface represent an early event in the development of some types of articular degeneration. We examined the ultrastructural appearance of the articular surface labelled in vitro with cationized ferritin in several age groups of a substrain of C57BL/6 mice that develop a high incidence of osteoarthritic-like lesions. We found that as early as the age of 2 1/2 months the articular femoral and patellar surfaces presented abnormalities that became more severe with age. Alterations of the articular surface is a precocious event in this type of osteoarthritic-like degeneration.

Aging in the T lymphocyte compartment. A developmental view.

A decline in the capacity of bone marrow cells to differentiate to T lymphocytes was found when cells from young and old donors were seeded onto an alymphoid fetal thymus. A step-by-step analysis of cell-cell interactions of the lymphohemopoietic cells and the thymic stroma indicated an effect of age on a variety of cell differentiation parameters. These included a decrease in the affinity of bone marrow cells to the stroma, and in their capacity to compete with the thymic lymphoid resident cells on colonization of the thymus. There was a significant decrease in the ability of cells of old donors to replicate sequentially within the thymic microenvironment. There was a reduced capacity of bone marrow cells from aging mice to express a developmental preference after seeding onto a syngeneic fetal thymus in a mixture with cells from allogeneic donors. We addressed the question whether the aging thymus contains increased levels of immature cells that fail to differentiate in the involuted thymic microenvironment by seeding thymocytes from young and old donors onto the fetal thymic stroma. The values of T cells that developed from the old donor inoculum were lower under these conditions. Our studies suggest that at least some of the manifestations of aging in the T cell compartment are related to developmentally programmed events in the lymphohemopoietic cell compartment.

Effects of growth hormone on thymocyte development from progenitor cells in the bone marrow.

The effect of growth hormone (GH) on T cell differentiation was studied in young and old mice, employing in vivo and in vitro experimental approaches. Injections of GH during a period of 3 months to young and old mice resulted in a significant increase in the cell number and the percentage of CD3+ cells in the thymus of the old, but not in the young mice. Treatment of intact fetal thymus (FT) lobes with recombinant human GH (hGH) had no significant effect on cell numbers or on the values of CD4/CD8 thymocyte subsets. When partially depleted FT (10 Gy) were colonized with bone marrow (BM) cells and subsequently cultivated on monolayers of GH3, a GH-secreting cell line, the values of T cells deriving from the donor BM cells were elevated. Treatment with hGH to cocultures of lymphoid-depleted FT (dGUA) with BM lent further support to the idea that GH affects the newly emigrating BM cells, rather than the resident thymocytes. The results suggest that GH affects the thymocyte progenitors in the BM at the early stage of their development in the thymus.

The effect of selective desalivation on wound healing in mice.

The effectiveness of wound licking in the acceleration of wound healing was evaluated in selectively desalivated mice. Rate of healing of experimentally induced cutaneous wounds was evaluated macroscopically by photography at 0, 2, 4, and 6 days after wounding. Sialadenectomy of submandibular and sublingual glands significantly slowed down wound healing in animals caged together compared to sham-operated controls. Separate caging as compared to caging in groups slowed down healing in sham-operated animals at day 2 but not at day 4 and 6. No effect on the rate of healing in sialadenectomized mice was observed in separate caging compared to mice caged in groups. Ligation of the parotid duct had an insignificant effect. The rate of wound healing of sublingual sialadenectomized mice was slower than that of sham-operated controls, but not as slow as those of sublingual and submandibular sialadenectomized mice. The results suggest that the rate of healing of experimentally induced cutaneous wounds of mice is slowed down when licking is prevented by separate caging which confirms previous reports. Licking with submandibular saliva seems to be more effective than sublingual saliva. Parotid saliva or minor salivary glands secretions are the least effective.

Interaction between macrophages and articular surfaces: an in vitro transmission and scanning electron microscopy study.

Interactions between macrophages and articular surfaces were studied in an in vitro model which has been described before. Either stimulated peritoneal macrophages or a purified population of bone marrow macrophages were incubated with mice femoral heads which were either untreated or were digested with collagenase, trypsin or hyaluronidase prior to incubation. Scanning electron microscopy (EM) examination showed that macrophages attached to the surface and in their vicinity tags and fibers were visible. Transmission EM was used after labeling the surfaces with cationized ferritin employed as a sensitive marker to define the integrity of the articular surface. Alterations of the surface of various degrees of intensity were seen in all the sections examined. No adhering macrophages were found, due probably to detachment of cells during tissue processing for transmission EM. Attachment of macrophages to the surface and alterations of the latter were seen also when hyaluronic acid was added to the incubation medium or when the surfaces had been treated with hyaluronidase before incubation.

The natural anti-alpha-galactosyl IgG on human normal senescent red blood cells.

A highly sensitive antiglobulin test based on rosette formation due to the interaction between IgG bearing red blood cells (RBC) and Fc receptors on K562 cells, was used to study the immunoglobulin molecules present on human senescent RBC. Normal human RBC were separated into young and senescent subpopulations on the basis of age-dependent differences in density by centrifugation on a discontinuous density Percoll gradient, and by flotation on phthalate ester mixtures. The senescent but not the young RBC were found to bear membrane bound IgG. Most of the bound IgG molecules could be specifically eluted by galactose in its alpha-anomeric form. Antigalactosyl (anti-Gal) IgG antibodies with similar reactivity were found to be present in high titres in every one of the 400 normal human sera tested. The natural anti-Gal antibodies isolated from normal sera by affinity chromatography could bind to IgG depleted senescent RBC but not to young RBC. Erythrophagocytosis experiments indicated that the anti-Gal bound to the senescent RBC induced their destruction by macrophages. It is suggested that the natural anti-Gal antibodies interact with cryptic alpha-galactosyl residues which are exposed in the course of the RBC senescence and mediate the removal of these RBC from circulation by cells of the reticuloendothelial system.

Interaction of macrophages with "old" red blood cells from syngeneic mice in vitro and the independence of the recognition process on macrophage Fc receptors.

The interaction between peritoneal macrophages and "old" red blood cells (RBC) from syngeneic mice was studied in vitro. It seems that this interaction is not mediated directly via Fc receptors on the macrophage. (1) 2-deoxy-D-glucose did not inhibit the phagocytosis of "old" RBC, but did inhibit the phagocytosis of IgG-coated sheep RBC (SRBC). (2) Immobilization of Fc receptors by plating macrophages on coverslips coated with bovine serum albumin: anti-bovine serum albumin (BSA: anti-BSA) complexes had no effect on the phagocytosis of "old" RBC, but inhibited the phagocytosis of IgG-coated SRBC. The interaction between mouse macrophages and "old" RBC is temperature dependent. At 4 degrees C and 22 degrees C "old" RBC attach to macrophages but are not phagocytized; at 37 degrees C phagocytosis occurs. Fetal calf serum (FCS) is required for optimal phagocytosis. Sialic acid residues on the macrophage surface do not play a role in this recognition and phagocytosis process, as neuraminidase treatment of macrophages did not affect the interaction.

Inhibition by tuftsin of Rauscher virus leukemia development in mice.

The antitumor effect of tuftsin, the natural phagocytosis-stimulating peptide, on leukemia induced by Rauscher murine leukemia virus (R-MuLV) was studied in vivo in SWR inbred mice. Tuftsin was found capable of significantly increasing the survival of R-MuLV-infected mice. The peptide, when injected both ip and iv into mice, exerted its activity in a dose- and time-dependent manner. Optimal antitumor activity was achieved upon administration of 25 micrograms tuftsin 4 days before R-MuLV inoculation.

Circadian fluctuations in the activity of phagocytic cells in blood, spleen, and peritoneal cavity of mice as measured by zymosan-induced chemiluminescence.

Circadian variations in the phagocytic activity of mouse whole blood, spleen, and peritoneal cells were studied using the zymosan-induced chemiluminescence assay as a measure of phagocytosis. On a regimen providing for light from 7:00 to 19:00 alternating with darkness, the phagocytic activity of mouse blood, spleen, and peritoneal cells was high around 10:00 and low around 22:00, the integrated counts of chemiluminescence being 82.33 x 10(5) and 52.76 x 10(5) for peritoneal cells, 83.3 x 10(5) and 32.2 x 10(5) for spleen cells, and 12.33 x 10(5) and 3.99 x 10(5) for blood cells. Variations of a similar tendency were also found in blood leukocyte and granulocyte counts, the counts being again higher at 10:00 compared with the blood samples withdrawn at 22:00. In contrast to the differences in the intensity of the zymosan-induced chemiluminescence, the shapes of the curves (Fig. 6) of each cell preparation were similar, irrespective of the time period of the day the cells were prepared. Comparison of the zymosan-induced chemiluminescence curves of the 3 cell suspensions studied, prepared at the same period of the day, revealed some similarity between the kinetics of blood and spleen samples; the intensity, however, of zymosan-induced chemiluminescence emitted by spleen cells was much higher. The kinetics of zymosan-induced chemiluminescence curves of peritoneal cells differed from the other 2, being slower at the onset, the chemiluminescence lasting for a longer time and declining more slowly. We have shown here circadian variations in the activity of mouse phagocytic cells. The simple and rapid method of chemiluminescence measurements used in this study appears to be a powerful tool for the further investigation of such circadian variations.

Possible involvement of macrophages in embryo--maternal relationships during ovum implantation in the rat.

Distribution of phagocytic cells in the rat endometrium during the estrous cycle and early gestation was examined by histological, electron microscopic, and histochemical techniques. The results show that numerous macrophages emerge around the nidus shortly after the onset of ovum implantation. Such macrophages, however, were not present within the decidua, suggesting that this tissue may be a protective barrier against the migration of phagocytic cells towards the implants. Approximately 48 hours after the onset of implantation, the number of endometrial macrophages decreased dramatically.

Phagocytosis of nucleated and mature beta thalassaemic red blood cells by mouse macrophages in vitro.

Physiological or experimental decrease in sialic acid (SA) content on the red blood cell (RBC) membrane is believed to play an important role in the recognition of these cells by macrophages. Since there is a 20-30% decrease in the SA content on the membrane of thalassaemic RBC, the interaction between macrophages and these RBC was studied in vitro. Using mouse peritoneal macrophages, it was found that these macrophages 'recognize' and phagocytize thalassaemic RBC while RBC from normal donors are hardly phagocytized. The average level of phagocytosis of thalassaemic RBC from splenectomized patients was found to be 22-fold higher than that of RBC from normal donors. The phagocytized cells consisted of both mature and nucleated RBC. Mouse peritoneal macrophages seem to be a useful in vitro system for the study of the accelerated sequestration and shortened life span of thalassaemic RBC.

Phagocytosis of 'old' red blood cells by macrophages from syngeneic mice in vitro.

We have studied in vitro the interaction of peritoneal macrophages with 'old' and 'young' RBC, as well as with enzymatically treated 'old' and 'young' RBC from syngeneic mice. 'Old' RBC were recognized and phagocytized by macrophages, whereas 'young' RBC were not. Neuraminidase treatment of both 'young' and 'old' RBC had little effect on the extent of phagocytosis. Trypsin treatment, on the other hand, markedly reduced the phagocytosis of 'old' RBC and had no effect on the phagocytosis of 'young' RBC. The level of phagocytosis of 'old' RBC by macrophages from mineral-oil treated mouse peritoneal cavities was roughly half that of macrophages from untreated mice. It is postualted that 'old' RBC could be recognized due to the presence of cytophilic antibodies on the surface of the macrophages. The specificity of these hypothetical cytophilic antibodies is believed to be directed towards sites which are absent or shielded in 'young' RBC, and exposed in 'old' RBC. Trypsin treatment of 'old' RBC appears to remove these antigenic sites from the 'old' RBC. The lower level of phagocytosis of 'old' RBC by mineral-oil induced macrophages could be due to the previous phagocytic activity of these cells, and their relatively uncoated, newly form plasma membrane, lacking cytophilic antibodies. In support of this hypothesis, we have demonstrated that trypsin treatment of macrophages resulted in a markedly decreased phagocytosis of 'old' RBC.