Biomedical subjects
Publications and source records attributed to H Valdimarsson.
Bone marrow cells were examined for the presence of IgG-Fc receptors using a red cell rosette technique. Receptors were demonstrated on some of the neutrophil promyelocytes, almost all of the neutrophil myelocytes, and a few of the eosinophil myelocytes. Cells which appeared on morphological grounds to be promonocytes also expressed Fc receptors.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
An antiserum with specificity for human T lymphocytes was evaluated as a diagnostic reagent in the clinical immunology laboratory. The antiserum was used in indirect immunofluorescence to detect T cells in blood samples from normal controls and patients with various disorders involving the immune system. The same samples were also examined using two established tests for T cells, the rosette reaction with sheep red blood cells (E rosette assay) and the proliferative response to phytohaemagglutinin (PHA). The antiserum and the rosette assay detected approximately the same numbers of T cells in controls, but the antiserum indicated T cell deficiency in several patients who appeared normal by rosetting or PHA reactivity. PHA stimulation in autologous plasma was depressed in a further group of patients who had normal T cell numbers by the other two tests. In vitro experiments with normal lymphocytes indicated that the E-rosette receptor was distinct from determinants detected by the T-cell specific antiserum. The immunofluorescence test with the anti-T serum provides an additional assay which appears to be more sensitive than the other two tests in detecting certain cases of T lymphocyte deficiency.
A new semiquantitative radiometric opsonin assay is described. It was found that the opsonin activity generated by incubating brewer's yeast, Saccharomyces cerevisiae, in medium containing less than 5% human serum was exclusively complement dependent. In contrast, C. albicans was effectively opsonized in the absence of complement. Antibodies and the early classical complement pathway did not contribute to the opsonization of S. cerevisiae and neither did C5-9. The brewer's yeast assay can therefore be used for measuring selectively the opsonizing capacity of the alternative pathway. Sera from approximately 7% of apparently healthy adult controls consistently failed to generate significant opsonin activity while 8 out of 26 patients with suspected immune deficiency of unknown cause were defective in this assay. All opsonin deficient sera so far tested had haemolytically normal alternative pathway and Factor B activity.
Inhibition of 3H-uridine incorporation into Candida albicans can be used as a sensitive index of phagocytic function because: 1) there is a linear correlation between uridine incorporation and yeast number; 2) phagocytic cells do not incorporate significant amounts of uridine in short term cultures; and 3) C. albicans replicating inside phagocytic cells does not take up uridine from culture medium. Appropriate conditions for measuring phagocytic capacity of human polymorphonuclear cells (PMN's) were 5 x 10(5) C. albicans and 5 x 10(4) PMNs in 0.5 ml of medium containing 2.5% AB serum. This mixture was incubated for 30 min at 37 degrees C. Aliquots were then transferred into microtiter wells and incubated for a further 60 min in the presence of 3H-uridine. Under these conditions PMN leucocytes from 25 healthy individuals caused suppression of uridine incorporation ranging from 33 to 75% (50 +/- 12).
Using new objective methods for measuring, independently, phagcytosis and killing, it was demonstrated that Candida albicans opsonized by C3-deficient serum was ingested by not killed in vitro by human polymorphonuclear leukocytes. Killing could be induced by adding purified C3 to the C3-deficient serum. It is concluded that C3 participates directely in the intracellular process leading to phagocytic killing of C. albicans.
The binding sites for sheep red cells (E) on human lymphocytes are trypsin-sensitive but regenerate in vitro on incubation at 37 degrees C. The rate of this regeneration was increased in the presence of dialysates of human leucocyte extracts (DLE). Thus incubation of trypsinized lymphocytes for 3 hr in appropriate dilutions of DLE resulted in a 2- to 6-fold increase of E-binding activity above that observed in medium-incubated control lymphocytes. Dialysates prepared from human thymus and brain similarly accelerated recovery of E-binding activity whilst dialysates of human fibroblasts and liver cells were inactive. The regeneration of trypsinized membrane immunoglobulin was slightly delayed in the presence of DLE. These findings indicate that leucocyte dialysates contain an activity which preferentially stimulates the regeneration of a T-lymphocyte membrane component. It is suggested that this activity may account for the immunological restoration observed in some patients with T-lymphocyte deficiency after injection of leucocyte dialysates.
Explore the source record for details and available documents.
Intracellular killing of Candida albicans was measured by a chromium release technique. Appropriate conditons were equal numbers of polymorphonuclear leucocytes (PMN) and 51Chromium labelled C. albicans (10 6/ml), fresh plasma at a final concentration of 2.5%, incubated at 37degreesC for 60 min. Using normal PMNs, 35-71% of releasable chromium was liberated into the supernatant under these conditions. This assay is easy to perform, requires a small amount of blood and offers and objective measurement of intracellular killing of C. albicans.
Congenital cytomegalovirus infection was found in an infant whose mother had a successful renal transplant and was treated with immunosuppressant therapy before and during pregnancy. Although so far not experiencing any untoward infections, the child had impaired T-lymphocyte function and subnormal serum-IgA.