Seroepidemiology of Toxoplasma gondii infection in the Israeli population.

Toxoplasmosis seroprevalence varies considerably between countries. We studied the seroprevalence of Toxoplasma gondii IgG antibodies in a national sample of the Israeli population; 2794 sera were tested. The highest age-adjusted seroprevalence rate was in Arabs (non-Bedouins) (60.4%), significantly higher compared to the rate in Jews (19.9%) and Bedouins (27.5%) (P < 0.01). There were no significant gender differences. Seropositivity increased with age in all population groups. For Jews, seropositivity was associated with place of birth and socioeconomic status. A finding of low seroprevalence rate in Bedouins despite their poor living conditions and close contact with livestock is surprising, and might be attributed to the dry and hot climate conditions in their area of residence. In women of reproductive age the seroprevalence was 15.1% in Jews, 25.4% in Bedouins and 72.3% in Arabs (non-Bedouins). Thus, the majority of pregnant women are susceptible to primary infection with T. gondii, and the risk for congenital toxoplasmosis remains high.

Enzyme immunoassay for the diagnosis of cat-scratch disease defined by polymerase chain reaction.

Whole-cell immunofluorescent antibody (IFA) tests for detection of anti-Bartonella henselae immunoglobulin (Ig) G are commonly used to diagnose cat-scratch disease (CSD). The need to cultivate B. henselae in Vero cells for antigen preparation and the absence of routinely applied IFA assays for IgM constitute the major disadvantages of this form of test. We describe the results of an enzyme immunoassay (EIA) for IgM and IgG that used N-lauroyl-sarcosine-insoluble outer membrane antigens from agar-grown B. henselae performed in 84 patients with definite CSD (regional lymphadenitis, cat contact, and > or =1 confirmatory test: polymerase chain reaction, skin test, or B. henselae culture). Although this method has been used as a diagnostic tool in several case reports, it has not previously been evaluated in a large study of definitively proven CSD cases. Results of this study indicate that the EIA described herein can play an important role in the serodiagnosis of CSD, although improvement of the sensitivity, particularly that of the IgM, would be desirable.

Adhesion characteristics of chondrocytes cultured separately and in co-cultures with synovial fibroblasts.

The present study was designed to investigate the adherence mechanism(s) and behaviour of cultured chondrocytes under various culturing conditions, co-culturing with fibroblasts, or growth in the presence of conditioned medium either of fibroblasts or chondrocytes. The findings obtained indicate that chondrocyte time-adhesion curves and the final percentiles of attached cells to a plastic substrate are much slower and lower respectively than those of anchorage dependent cell types. The poorest adhesion occurs employing chondrocytes originated from suspension cultures, as compared to chondrocytes grown in monolayers. No interference with chondrocyte adhesion was found by inhibiting the production of proteoglycan (PG). Puromycin and to a lesser degree actinomycin but not cytosine arabinoside interfered with chondrocyte adhesion, suggesting the importance of protein synthesis in this process. The nature of proadhesion modifying molecules in synoviocytes conditioned media and antiadhesive agents in chondrocyte conditioned media suggests that both substances are heat labile, non-dialyzable, protein containing factors.

Enhanced repopulation of murine hematopoietic organs in sublethally irradiated mice after treatment with ciprofloxacin.

We analyzed the effect of ciprofloxacin, fleroxacin, and ceftazidime on production of colony-stimulating factors (CSF) by cultured murine spleen cells in the presence of pokeweed mitogen (PWM). Ciprofloxacin at concentrations of 5 to 10 micrograms/mL in concert with PWM stimulated CSF production by cultured spleen cells. A 3.5-fold increase in the number of CFU-C was observed in the presence of ciprofloxacin-PWM spleen conditioned medium (SCM) as compared with control cultures exposed to PWM-SCM only. Antimurine GM-CSF and antimurine interleukin-3 (IL-3) antibodies inhibited colony formation stimulated by PWM-SCM or ciprofloxacin-PWM-SCM. Fleroxacin and ceftazidime at concentrations of 1 to 100 micrograms/mL and ciprofloxacin at high concentration (greater than 10 micrograms/mL) either did not affect CSF production by spleen cells or had an inhibitory effect. In vivo treatment of sublethally irradiated (650 rad) mice with ciprofloxacin (15 mg/kg per dose three times daily for 5 days) resulted in an increased number of myeloid progenitors in the spleen and bone marrow (BM) of treated mice. In contrast, treatment with ceftazidime did not affect progenitor cell numbers. On days 4 and 8 postirradiation ciprofloxacin-treated mice had a 2.3- and 3.8-fold increase, respectively, in the number of CFU-C in the BM. The number of CFU-C in the spleen did not increase on day 4 postirradiation, but on day 8, the number increased 1.7-fold. On day 4 postirradiation, sublethally irradiated mice treated with ciprofloxacin had a higher WBC count, RBC count, and hemoglobin level as compared with ceftazidime- and saline-treated mice. Twenty-four days postirradiation, 45% of saline-treated mice (20 of 44), and 35% of ceftazidime-treated mice (8 of 23) died, as compared with 13% (5 of 38) of ciprofloxacin-treated mice (P less than .05). These studies indicate that ciprofloxacin may have an immune-enhancing effect on the hematopoietic system in neutropenic mice.

Enhanced resistance of bone marrow transplanted mice to bacterial infection induced by recombinant granulocyte-macrophage colony-stimulating factor.

The in vivo effect of recombinant murine granulocyte-macrophage colony stimulating factor (rGM-CSF) on the resistance of mice to bacterial infection and on the number and function of neutrophils was studied in lethally irradiated mice transplanted with syngeneic bone marrow cells. Bone marrow transplanted (BMT) mice were injected intraperitoneally with 150 ng rGM-CSF or buffer solution (diluent) twice daily for 18 consecutive days. Total neutrophil recovery from the peripheral blood and the number of neutrophils mobilized into the peritoneal cavity were accelerated in rGM-CSF-treated recipients. Peritoneal neutrophils isolated from mice treated with rGM-CSF exhibited primed superoxide generation (O2-) after in vitro stimulation with suboptimal concentrations of phorbol myristate acetate (PMA), as compared with control mice (treated with diluent). No additional increase in O2- production occurred upon in vitro incubation of these cells with rGM-CSF. The protective activity of rGM-CSF was examined in mice injected with Salmonella typhimurium. There was a 44- and 9-fold increase in the number of S typhimurium at 96 hours postinfection in the spleen and liver, respectively, of control mice, as compared with rGM-CSF-treated mice, after a single injection of the bacteria (3 X 10(7) per mouse). All the untreated control mice died within 14 days postinoculation (1 X 10(7) bacteria per mouse), whereas 35% of the mice treated with rGM-CSF remained alive for more than 30 days postinfection. These findings support the concept that increased granulopoiesis and enhanced functional activity of phagocytic cells is induced by rGM-CSF and is responsible for enhanced resistance of BMT mice to bacterial infection.

Induction of murine macrophage fungal killing by interleukin 3.

The effect of recombinant interleukin 3 (IL-3) on the function of murine resident peritoneal macrophages was investigated. IL-3 enhanced the phagocytosis of Candida pseudotropicalis and Candida albicans and enhanced killing of the former. The enhanced killing is inhibited by scavengers of oxygen radicals, suggesting that IL-3 primes macrophages for enhanced oxidative metabolism in response to Candida.

Biological properties in vitro of a combination of recombinant murine interleukin-3 and granulocyte-macrophage colony-stimulating factor.

The effect of recombinant murine interleukin-3 (rIL-3) and recombinant murine granulocyte-macrophage colony-stimulating factor (rGM-CSF) on in vitro murine myeloid progenitor cell (CFU-C) growth and on the function of murine resident peritoneal macrophages was investigated. Both rIL-3 and rGM-CSF are known to support the growth of CFU-C and, when combined, were found to act synergistically to induce the development of an increased number of CFU-C. The distribution pattern of myeloid colonies in the presence of these two growth factors was in general similar to that in the presence of rGM-CSF alone. Both rGM-CSF and rIL-3 enhanced the phagocytosis of Candida albicans (CA) by mature macrophages producing an increase in the percentage of phagocytosing cells as well as an increase in the number of yeast particles ingested per cell. No additive effect on the phagocytosis was observed when the two growth factors were added concurrently. rGM-CSF, but not rIL-3, enhanced the killing of CA by macrophages. This killing was inhibited by scavengers of oxygen radicals.

Enhanced reconstitution of hematopoietic organs in irradiated mice, following their transplantation with bone marrow cells pretreated with recombinant interleukin 3.

Lethally irradiated C3H/eb mice were injected with syngeneic bone marrow cells that had been exposed for 4 h in vitro to purified bacterially synthesized interleukin 3 (rIL-3). Control mice were injected with cells exposed to incubation medium only. Mice injected with rIL-3-treated cells exhibited, on day 10 after transplantation an 8.2-fold and 2.7-fold increase in number of myeloid progenitors in their spleen and bone marrow, respectively, but the in vitro differentiation pattern of the myeloid progenitors was not affected. There was, however, an increase in the number of cells per individual in vitro myeloid colony (CFU-C) of the rIL-3-treated mice. The latter mice also showed a 1.6-fold increase in the number of splenic colony-forming units (CFU-S), a higher self-renewal capacity of hematopoietic progenitors, and a higher number of leukocytes in the peripheral blood. These results indicate that the injection into lethally irradiated recipients of bone marrow cells briefly pretreated in vitro with rIL-3 significantly enhances the reconstitution of their hematopoietic organs, and suggest that the in vitro pretreatment of bone marrow cells with appropriate stimulating factors could be useful in bone marrow transplantation.

The effect of low dose ARA-C on in-vitro haemopoiesis of marrow cells from myelodysplastic patients.

The effect of low dose (10(-12)-10(-7) M) ARA-C on differentiation and proliferation in liquid and semisolid culture of marrow cells from 13 patients with myelodysplastic syndrome (MDS) were studied following incubation in liquid culture with low dose ARA-C. In six of ten patients an increasing number of myeloid cells acquired the morphologic appearance of mature monocyte-macrophages. Increasing number of cells reacted positively to fluoride sensitive naphthyl acetate esterase and specifically bound MY4 monoclonal antibody. Phagocytosis and killing of Candida albicans by monocyte-macrophages incubated with low dose ARA-C was normal and similar to that of the untreated cells. All MDS patients showed reduced myeloid colony and increased cluster formation. Low dose ARA-C had slight but non-significant inhibitory effects on myeloid colony growth. The results indicated that the differentiation pattern of myeloid precursor cells form a subset of MDS patients was altered by exposure to low dose ARA-C in vitro.

In vitro hemopoiesis of marrow cells from myelodysplastic patients: effects of mitogen-stimulated spleen cell-conditioned medium and vitamin A and D derivatives.

We determined the ability of pokeweed mitogen-stimulated human spleen cells to support the growth and proliferation of hemopoietic progenitors from normal and myelodysplastic syndrome (MDS) patients, in the presence and absence of the maturation-inducing agents 13-cis-retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (vit D). The addition of various concentrations of vit D or RA to culture plates containing MDS patients' marrow cells stimulated myeloid colony growth. A higher number of myeloid colony-forming units-cell was noted in cultures containing vit D or RA in addition to pokeweed mitogen spleen-conditioned medium compared to these substances and placenta conditioned medium. When colony-forming units-cell from MDS patients was incubated with 2 X 10(-8) M vit D the percentage of monocyte-macrophage colonies was increased and the number of granulocyte colonies was decreased. Neither vit D nor RA affected the number of cells per colony. Our findings suggest that pokeweed mitogen spleen-conditioned medium provides a more potent source than placenta-conditioned medium for humoral factors that stimulate the growth of hemopoietic progenitors from MDS patients and that the use of pokeweed mitogen spleen-conditioned medium may improve studies of hemopoiesis in MDS patients.

Effect of 1,25 dihydroxyvitamin D3 and retinoic acid on normal human pluripotent (CFU-mix), erythroid (BFU-E), and myeloid (CFU-C) progenitor cell growth and differentiation patterns.

The modulatory effect of 1,25 dihydroxyvitamin D3 (vit D) and 13 cis retinoic acid (retinoic acid) on the growth and differentiation of normal human pluripotent stem cell, erythroid, and myeloid progenitor cell growth was studied using semisolid methylcellulose clonal assay. Dose response curves showed that maximal increments of myeloid colony (CFU-C) growth (150%) occurred with vit D at 2 X 10(-9) -2 X 10(-8) M and with retinoic acid (184%) at 1 X 10(-7) M. Vit D caused a 134% increase in macrophage colonies (CFU-M) and a decrease in granulocytic (CFU-G) and granulocyte-macrophage colonies (CFU-GM) (50% and 58%, respectively, as compared to the control). Retinoic acid did not alter the differentiation pattern of myeloid colonies (CFU-M, CFU-G, and CFU-GM). Vit D at 2 X 10(-8) M had an inhibitory effect on BFU-E (62% growth of control) and did not affect CFU-mix growth. Retinoic acid at 10(-7) M did not alter the growth of either BFU-E or of CFU-mix. Cellular differentiation studies in liquid suspension showed that vit D caused a 213% increase in monocyte-macrophages and a 56% and 26% decrease in immature and mature granulocytes, respectively. Retinoic acid caused a marked (79%) decrease in immature granulocytes whereas the percentage of mature granulocytes and monocyte-macrophages was not changed. Assessment of phagocytosis and killing of Candida albicans (C.A.) by cultured monocyte-macrophages and granulocytes exposed to vit D and retinoic acid demonstrated that treated cells had the same capability to phagocytose and kill C.A. as did untreated cells.