Spleen tyrosine kinase expression in patients with chronic immune thrombocytopenia

Objective: By conducting a Spleen Tyrosine Kinase (SYK) expression study, which is known to be associated with thrombocyte degradation activities of macrophages in the spleen, we aimed to determine SYK activity in both patients followed up with chronic ITP and in the control group. Material and Method: Thirty-five ITP patients aged 1-18 years with chronic ITP who applied to the Hematology Outpatient Clinic of Çukurova University Faculty of Medicine were included in this study. Fifteen patients in the same age group who applied to the Healthy Child Outpatient Clinic, who did not have any hematological problems except for iron deficiency anemia, and showed no signs of infection on physical examination were included as the control group. The time of diagnosis of the patients included in the study, the history of infection before the diagnosis (URTI, LRTI, rash disease within last 1-4 weeks), white blood cell count, hematocrit, thrombocyte count, monthly platelet course, autoantibodies and treatments received were evaluated. The families of the age and sex matched children were informed, blood samples were taken into EDTA tubes while other blood tests were taken, and the SYK activation value was measured. Findings: The mean age of 35 patients included in our study was 9.1±4.17 years, and the mean age of the control group was 8.45±5.08 years. The female / male ratio was found to be 0.7 in our cases. History of previous infection (HPI) was present in 25.7% of the cases and vaccination history was present in 2.9%. The ratio of patients who were found to be positive in viral serology evaluation to the number of patients examined were as follows; EBV IgG 11/35 (31.4%), Toxoplasma IgG 1/35 (2.9%), Rubella IgG 1/35 (2.9%). The mean SYK activation value of the evaluated patients was 2.2±3.14, and the mean SYK activation value of the control group was 2.1±2.55. There was no statistically significant difference between the mean SYK activation values of the patient and control groups (p = 0.65). When the baseline and mean platelet values, which were categorized as 3 groups in the patient and control groups, and mean SYK activation values were compared, no statistically significant difference was found (p=0.934, p=0.264). Regarding the treatments given, although there was no significant difference in SYK activation between those who received methylprednisolone and IVIG treatment and those who did not (p = 0.595, p = 0.382), there was a borderline significant difference between patients who received and did not receive dexamethasone (p = 0.05). When the patients who received and did not receive Eltrombopag (Revolade) treatment were compared, a statistically significant difference was found in terms of mean SYK activation value (p = 0.06). Conclusion: ITP is a common disease in childhood and 20-30% of patients become chronic. When we look at the mean SYK activation value, which is an important part of our study, it was found that there was no relationship between hematological data and SYK activation. The initial and mean platelet values of the patients were categorized into 3 groups and when evaluated in terms of SYK activation, no significant difference was found. Among the treatments given, the fact that the average SYK activation value was found to be lower in the Revolade patients compared to those who did not take it, the improvement of the clinical findings and the increase in thrombocyte values indicate that the drug has an important place in the treatment of patients with ITP. As a result, SYK activation is expected to be high in patients with ITP, but in our study, the expected values were not obtained due to the limited number of patients. There are no studies in pediatric patients on SYK inhibitors, which are thought to increase the platelet count in adult patients with ITP by reducing phagocytosis by inhibiting Fc-activating receptors and signal transduction via B-cell receptors, and by destroying autoantibody-coated platelets by macrophages. Studies on the relationship between spleen tyrosine kinase expression and ITP in larger case series may contribute to the understanding of the pathophysiology of ITP and help support new treatment searches. Keywords: chronic immune thrombocytopenia, spleen tyrosine kinase, SYK activation value