This question was posted on Wednesday, May 23 on Pat Letendre’s Medlab list and is reposted here with Linda Stang’s permission: We have a patient with lymphoma and an IgG peak (we think). The antibodies are interfering (and I mean really interfering) in the coags: INR >5.0 but has had clinical challenges with no bleeding. Is there any way to remove IgG from samples? I am currently trying a heterophile blocking tube (HBT) hoping that it will neutralize the antibodies. Does anyone know of any other method to remove unwanted IgG from a sample, but have it remove little else? Thanks in advance for any suggestions.
Linda Stang MLT
Lab Scientist, Special Coagulation & Flow Cytometry
University of Alberta Hospital, Edmonton, Alberta, Canada
And an added comment, Friday, May 25, from Linda: The HBT tube did correct the INR somewhat, but only from 4.9 down to 3.9 (3.4 if I were to use 2 HBT tubes), and the appropriate controls did not vary much with the HBT treatment. The INR is consistently 4.8–6.0 with different reagents/analyzers, PTT is 48 or 80, depending on the PTT reagent used. I am considering purchasing a protein G column, but am a little scared of how the coag will be affected. Surgery is on hold, with us trying to verify that the underlying coags are normal.
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Late reply…thrombin times were all normal, warming the sam
Late reply…thrombin times were all normal, warming the sample for 1 hr at 37C did not change results – but was a good idea to try, none the less. Patient has had chemo now (never did go for the surgery because of the critical INR), and post chemo has had an [almost] normal INR.
Lymphomas with IgM antibodies are more common tha
Lymphomas with IgM antibodies are more common than IgG-secreting lymphomas; unless you are talking about plasma cell neoplasms where IgG secretion is common. IgM lymphomas will manifest like any other cold agglutinin disease. So how about trying the conventional method of incubating the sample at 37 degrees for 15 minutes before performing the test to see if there is any correction?
What is the lupus anticoagulant status? Some thromboplastins
What is the lupus anticoagulant status? Some thromboplastins may give anomalously high results, for instance, Innovin and other recombinant thromboplastins with some patients only. Could be IgG or IgM in our experience. Is this a paraprotein? What is the thrombin time?
Hi Linda, Have you tried mixing studies with normal pooled p
Hi Linda, Have you tried mixing studies with normal pooled plasma (NPP) to rule out factor deficiency/liver impairment etc? Running serial dilutions of the patient sample in NPP with & without pre-incubation will tell you if fast or slow reacting antibodies exist against coagulation factors (parallelism/non-parallelism rule). Back to your question, removing normal human IgG from plasma per se doesn’t affect significantly coagulation result. I have done it before. However, if we are dealing with Ab against targets which are involved in coagulation, then you have to make sure other than Ab no active pro/anti-coagulant proteins remain on the column. Otherwise, interpretations of your next coagulation tests are still open to questions. Dr. Ali Sadeghi-Khomami, PrecisionBioLogic