Biomedical subjects
D K Powell
Publications and source records attributed to D K Powell.
Enzyme linked immunoassay for the detection of platelet associated IgG.
An enzyme linked immunoassay incorporating antihuman globulin coupled with alkaline phosphatase has been developed to measure platelet associated IgG (PAIgG). Using a method in which platelet IgG is extracted into the fluid phase after appropriate procedures, we were able to bind the 'solubilized' PAIgG to commercially obtained antihuman IgG (AHG) which had previously been coated onto polystyrene. The amount of PAIgG thus bound was subsequently measured by the addition of the enzyme reagent using p-nitro phenyl phosphate as substrate. With this technique platelets from normal donors were found to have 2.6-17.4 ng/10(6) platelets (mean +/-2 SD). These values are higher than those obtained when assay systems using intact platelets are employed. Platelets from patients with immune thrombocytopenia had PAIgG values of 8.2-98.0 ng/10(6) platelets. In a few patients with disorders other than autoimmune thrombocytopenia (AITP) increased levels of PAIgG were also demonstrated. The assumption that increased PAIgG always represents platelet autoantibody may not be valid. The relevance of PAIgG as a parameter in the diagnosis and clinical management of patients with AITP is discussed.
'Sun never sets' for staff in prevention-oriented practice.
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Detection of platelet-bound and serum antibodies in autoimmune thrombocytopenia by enzyme-linked assay.
Platelet antibodies were looked for in 47 patients with autoimmune thrombocytopenia using a modification of the enzyme-linked assay previously described. Surface-bound antibodies measured as increased platelet-associated IgG were found in 32 (68%) of the patients. After incubation in test sera, the platelet-associated IgG of normal donor platelets was significantly increased in 27 of the 47 patients (57%), thus demonstrating the presence of platelet antibodies free in their sera. 6 patients had antibodies only in the serum without any elevation of their platelet-associated IgG. When both tests are evaluated together no antibody was detected by either the direct or the indirect test in 9 of the 47 patients (29%) studied. The technique used is described and the interpretation of our results discussed.