Erythropoiesis and lymphopoiesis in the chick yolk-sac-embryo chimeras: contribution of yolk sac and intraembryonic stem cells.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk-sac-embryo chimeras differing at the B locus antigens. Erythroid cells derived from the yolk sac or from the intraembryonic mesenchyme were demonstrated by indirect immunofluorescence in the peripheral blood of these allogenic chimeras. At 7 days of incubation, yolk-sac-derived red cells represent a majority in the peripheral blood.

Migration of erythropoietic and prebursal stem cells from the early chicken embryo to the yolk sac.

Lymphocyte development and ontogenetic changes in erythroid cells have been studied in chick-chick yolk sac-embryo chimeras constructed of histoincompatible partners. The results obtained indicate that the early chick yolk sac produces transiently erythroid stem cells whereas definitive erythrocytes are derived from the intraembryonic stem cells. Such a change from the yolk sac-derived cells into embryo-derived cells is not observed in the lymphocytes which are exclusively derived from the embryo-borne stem cells.

Ceftazidime in the treatment of urinary tract infection.

Twenty-nine patients with urinary tract infection were treated with ceftazidime intramuscularly, at a dosage of 1000 mg twice daily for 7 days. The patient series was predominantly geriatric, with a mean age of 70.9 years and including 17 patients over 75 years.

Studies on the chicken lymphocyte receptor for aggregated IgG.

Chicken lymphocytes isolated from different lymphoid organs were analyzed for Fc IgG receptor by binding of heat aggregated IgG (agg IgG) in the indirect immunofluorescence test. The binding of agg IgG was shown to be specific for Fc IgG receptor, since IgM and F(ab')2 fractions were bound to the lymphocytes in a much less degree. The highest frequency of agg IgG binding cells, almost 100%, was found in the bursa of Fabricius.

T cell dependent B cell differentiation in the chicken.

Transplantation of bursa cells into surgically thymectomized (STx), cyclophosphamide(CY)-treated and X-irradiated (X) newly hatched chicks resulted in a morphological and functional reconstitution of the bursa-dependent immune system only when the transplanted bursa cells were supplemented with thymus cells. Without supplementation with thymus cells, morphological restoration of the bursa, antibody formation to sheep red blood cells and Brucella abortus, and germinal center formation remained deeply deficient. Bursa cells alone induced a full reconstitution of the bursa-dependent immunity in non-thymectomized.

Enhancing effect of surgical bursectomy on antibody response.

Effect of surgical bursectomy on antibody response was studied in chicks injected intrabursally with sheep red blood cells (SRBC) and Brucella abortus on day 2 of life and challenged intravenously with the same antigens on day 9. Bursectomy performed 2 days after the priming resulted in a significantly decreased anti-SRBC plaque-forming cell (PFC) response, whereas bursectomy performed 4 or 5 days after the priming clearly enhanced the PFC response. The enhancing effect of bursectomy on the PFC response was also observed if the priming was made intravenously.

A rosette assay for identification of Ia-like alloantigens on chicken lymphoid cells.

An Ia-rosette assay for the detection of Ia-like alloantigens on the chicken lymphoid cell surface is described. The method is based on the ability of cells treated with alloantiserum to Ia and then with rabbit antiserum against the Fc portion of chicken IgG, to form rosettes with sheep erythrocytes (SRBC) coated with chicken anti-SRBC IgG antibody. Interference with Ia-rosette formation by Fc IgG receptors was eliminated by pronase treatment which removes Fc receptor activity without affecting Ia antigens.

Effect of trimethoprim or trimethoprim/sulphamethoxazole usage on the emergence of trimethoprim resistance in urinary tract pathogens.

The frequency of trimethoprim (TMP)-resistant bacteria isolated from urine was studied in hospitals, in Stockholm, Sweden, and Turku, Finland. TMP has been in clinical use in Finland since 1973, whereas in Sweden TMP was available only in combination with sulphamethoxazole (SMZ) at the time for this study. All samples were collected solely from in-patients at 4 different occasions during a 20-month period 1977-78.

Mother/child mixed lymphocyte reaction: is it depressed?

Several alternative reasons have been offered for the immunological inertia between the pregnant mother and her fetus. None of these alone has proved correct and sufficient. In this review Paavo Toivanen and Christer Granberg look at one interesting mechanism - the inhibition of maternal lymphocyte reactivity by fetal suppressor cells observedin vitro when untreated populations of maternal and neonatal lymphocytes are cultured together.

Effects of intrauterine thymectomy on mitogen response in guinea pig.

Intrauterine thymectomy was carried out on days 36, 40, 48 and 68 (neonatal) of foetal life to investigate the role of thymus and emigration of thymocytes in the development of mitogenic (PHA, Con A, DxS) responses in the guinea pig. The results provide further evidence that emigration of thymocytes is a continuous process which takes place already at the time of demarcation between thymic cortex and medulla (before day 36 of gestation) and again immediately after birth. In the lymph nodes of guinea pigs thymectomized on day 36 in utero a small PHA and Con A responding cell population exists at the time of birth but not any more 3-4 mth later.

Trimethoprim resistance in Finland after five years' use of plain trimethoprim.

A total of 1388 urinary bacterial pathogens were tested for resistance to plain trimethoprim after five years' use of this drug for prophylaxis against urinary tract infections. Samples were obtained in Turku, Finland, where use of the drug is much greater than in other parts of Finland. Resistance to trimethoprim (greater than 8 mg/l; agar-dilution method) occurred in 20.

Lymphoid stem cells in the intraembryonic mesenchyme of the chicken.

Chromosomally marked cells from the 7-day intraembryonic mesenchyme were transplanted into 14-day-old irradiated chick embryos. At the age of 6 weeks donor-derived T and B lymphocytes were shown to be present in the thymus, spleen and bone marrow, indicating that cells in the 7-day intraembryonic mesenchyme are capable of developing into functional T and B lymphocytes. In addition to the sex chromosome marker, IgG allotype was used as a marker; the results demonstrate that cells from intraembryonic haemopoietic sites develop into mature IgG-producing cells.

Cell-mediated lympholysis by human maternal and neonatal lymphocytes: mother's reactivity against neonatal cells and vice versa.

Maternal reactivity in cell-mediated lympholysis (CML) against cells from her own child is, in average, half of the maternal reactivity against unrelated adult cells. This finding remains the same when cells from a newborn or from an older child are used, suggesting that the reduced maternal reactivity is based rather on the one haplotype identity between the mother and child than on the occurrence of specific maternal tolerance. Consistently, CML-capacity of the child, directed against cells of own mother, is half of the control values, again independently of the child's age.

Prebursal stem cells in the intraembryonic mesenchyme of the chick embryo at 7 days of incubation.

Cyclophosphamide-treated 18-day-old chick embryos were transplanted with cells from 7-day intraembryonic mesenchyme; the recipients and donors were identical at the major histocompatibility locus. At the age of 35 days, the cell recipients were studied to determine the reconstitution capacity of the transplanted cells. The transplantation resulted in a complete restoration of IgM and IgG class antibody production against human gammaglobulin and Brucella abortus, and of microscopic morphology of the bursa of Fabricius and of the germinal center formation in the spleen.

Intraembryonic origin of lymphoid stem cells in the chicken: studies with sex chromosome and IgG allotype markers in histocompatible yolk sac-embryo chimaeras.

Two-day-old chick embryonic bodies were transplanted onto the area vasculosa of age-matched histocompatible blastoderms, resulting in the development of yolk sac-embryo chimaeras. Eighteen of these succeeded in hatching and became adults. Differences in the sex chromosomes and in IgG allotype between the embryo and the yolk sac were used to study the contribution of these two components to the lymphoid cell development.