engleski

Testing of granulocyte-associated antibodies (GA- ABS), part II: application to the adult patient testing

Introduction:Although GA-Ab tests are impaired by non-specific adsorption ofantibodies, small improvements may potentially contribute to their re-employment inleukopenia diagnostics.Materials and Methods:Eighty duplicated GA-Ab tests were performed in 77 adultpatients, as described in abstract, part I: 16 tests in patients with autoimmune neu-tropenia (AIN) (15 with collagen diseases, one with primary form), 5 in other immunedisorders, 8 in non-immune leukopenias and 51 in patients not re-appearing or lackingdefinitive diagnosis. Patients were followed for diagnosis 2 years after initial tests.Results:With cut-off at 1.5 SD over negative control (NC), significant difference wasobserved between AIN and non-immune patients (68.7% and 12.5%, respectively, P < 0.01), along with cut-off at 3 SD (P < 0.02). With cut-off at 50% over NC, thisdifference (62.5% vs. 25% positive tests) was only close to significance (P = 0.083).Furthermore, no non-immune patient showed >2 SD reading, compared to 11 (68.8%)AIN and 2 (40%) other immune patients (P < 0.01). Out of 11 AIN patients tested byDako (Glostrup, Denmark), 4 were IgG and 7 IgM positive, compared to 2 IgG and 4 IgMof 5 AIN patients tested by Jackson (West Grove, PA ; USA) (n.s.). 8 AIN samples with<7·109/L of isolated granulocytes showed 3 IgG and 5 IgM positive tests, comparedto 3 IgG and 6 IgM positive tests in 8 samples with >7·109/L cells (n.s.).Nevertheless, IgG tests were positive in 5/9 (55.6%) untreated AIN patients, compared to 1/7 (14.3%)patients treated with corticosteroids (P = 0.09). IgM test was positive in 5 untreated and6 treated patients (n.s.). IgG patient readings (in SDs) was significantly higher in 20fresh samples sent to our hospital (11.7 ± 25.1) than in 43 samples drown at our and 17at other hospital departments (1.8 ± 3.5 and 2.4 ± 5.9, P < 0.02 and P < 0.03, re-spectively). Similarly, IgM readings were positive in 25 (62.5%) sent samples, comparedto 27 (31.4%) and 13 (35.3%) samples taken in our hospital (P < 0.004).Conclusions:It seems that setting at 2 SD over NC present rather safe cut-off forpointing to immune origin of the disease, with almost 70% AIN and 40% immunediseases having positive IgG or IgM test. While reagent and granulocyte concentrationhad no impact on test performance, corticosteroid therapy seemingly impaired IgG testresults. Therefore, IgM tests, not influenced by the drug, seem to be important part ofthe testing. Finally, transport of samples, although tested within 6 hours, mightinfluence patient test outcome

granulocyte-associated antibodies (GA-ABS)

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