Premium
Increased levels of platelet associated IgG in patients with thrombocytopenia are not confined to any particular size class of platelets
Author(s) -
Holme S.,
Heaton A.,
Kunchuba A.,
Hartman P.
Publication year - 1988
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1988.tb04231.x
Subject(s) - platelet , flow cytometry , chemistry , antibody , immunology , microbiology and biotechnology , medicine , biology
Summary Patients with immune thrombocytopenia have an increased percentage of microthrombocytes/platelet fragments and megathrombocytes. It has been suggested that increased levels of platelet associated IgG (PA‐IgG) found in these patients might be related to the presence of this abnormal platelet size distribution. In this study we used flow cytometry to investigate the distribution of PA‐IgG within a population of platelets and, in particular, we examined the relationship between platelet size and PA‐IgG determined simultaneously on individual platelets. Platelet samples from 10 normals and 31 thrombocytopenic patients were studied. PA‐IgG was estimated using immunofluorescent FITC anti‐IgG antibody. Binding of FITC anti‐IgG to the platelets was quantitated in the flow cytometer as relative mean fluorescence (RMF) which was calibrated against values (in fg/plt of FITC anti‐IgG) obtained by spectrofluorometry after solubili‐zation of the platelets. A high correlation ( r 0.89) was found between flow cytometric RMF value and spectrofluorometric FITC anti‐IgG values. The flow cytometric studies showed that platelet samples with abnormally elevated levels of FITC anti‐IgG (>1.7 fg/plt) not only have a higher percentage of platelets with elevated FITC anti‐IgG, but that these platelets also have increased levels of FITC anti‐IgG as compared to platelets from normal samples. Platelet size was measured by the amount of forward light scatter in the flow cytometer. A low but significant correlation ( r =0.33±0.12) was found between size (FALS) and fluorescent signals in samples with elevated FITC anti‐IgG. The contribution of 10% of the smallest platelets by FALS and 10% of the largest platelets by FALS to the total levels of flow cytometer platelet fluorescence in these samples was only 4.4% and 19.4% respectively which was not higher than obtained with samples with normal levels of FITC anti‐IgG. In conclusion. this study showed that increased levels of PA‐IgG found among thrombocytopenic patients were not confined to any particular size class of platelets.