European journal of haematology
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Heparin-induced thrombocytopenia (HIT) is usually caused by anti-platelet factor 4 (PF4)/heparin antibodies, leading to intravascular platelet activation. These antibodies can be detected by PF4/polyanion antigen assays or platelet activation assays. While antigen assays are very sensitive and recognize immunoglobulin (Ig)G, IgA, and IgM antibodies, the role of IgM and IgA HIT-antibodies is debated. Platelet activation assays recognize IgG and are more specific for clinical HIT. ⋯ Detection of IgG, IgM and IgA class antibodies by PF4/heparin ELISA yields a positive test result about twice as often as does a platelet activation assay, with only a minority of the additional patients detected likely having HIT. Thus, there is a potential for considerable over-diagnosis of HIT by laboratories that utilize only an ELISA for diagnostic testing.
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Studies performed on mice and healthy human volunteers have shown that a single dose of pegfilgrastim (Peg-GCSF) is effective in stimulating peripheral blood stem cells (PBSC) mobilization. This prompted us to try the stimulation with pegfilgrastim in a patient previously non-mobilizing with a combination of chemotherapy and filgrastim. In December 2003, a 65-yr-old man was diagnosed as having stage III A IgG/k multiple myeloma. ⋯ He experienced a sustained engraftment and maintains complete remission 9 months after the reinfusion. In conclusion, a single dose of pegfilgrastim was able to mobilize a sufficient number of CD34+ in a multiple myeloma patient not responsive to two previous attempts with high or standard dose chemotherapy followed by filgrastim. This approach, if confirmed on larger series and other diseases, could open new opportunities in stem cell mobilization for poor or non-mobilizers.