Human platelet antigen 1, 2 and 5 gene polymorphisms in Egyptians and their potential association with susceptibility to immune thrombocytopenic purpura in Egyptian patients.

OBJECTIVES: This study determined the incidence of HPA1, HPA2 and HPA5 polymorphisms in 120 Egyptian immune thrombocytopenic purpura (ITP) patients and 120 healthy Egyptian subjects. METHODS: Human platelet antigen (HPA) genotyping was done using the polymerase chain reaction-restriction fragment length polymorphism. RESULTS: The frequency of HPA1 allele a and b was 78.75 and 21.25% in controls, 80.8 and 19.2% in ITP, respectively. HPA2 allele a and b frequency was 86.25 and 13.75% in controls and of 74.6 and 25.4% in patients, respectively. HPA5 allele a and b frequency was 87.5 and 12.5% in controls, in patients it was 85 and 15%, respectively. With the exception of HPA2, no other significant difference was encountered in HPA allele frequency between controls and ITP patients. DISCUSSION: Egyptian HPA profile is closely linked to Middle East and neighboring Arabs. The current study noted that in all the studied HPA systems 1, 2 and 5, the 'a' allele is more prevalent than the b allele; the most frequent genotype was the homozygous a/a genotype. HPA2b frequency, homo- and hetero-zygous HPA2b genotype frequencies were significantly higher in ITP patients compared to controls. CONCLUSION: HPA 2b are 2.37 times more likely to develop ITP compared to those without this allele. The relatively high allele frequency of the HPA-1b in the Egyptian population suggests that this ethnic group has a higher risk of alloimmunization.

The potential association of tumor necrosis factor-ßeta (252 G/A) cytokine gene polymorphism with immune thrombocytopenic purpura among Egyptian children.

OBJECTIVES: The main objective of this study was to study tumor necrosis factor beta (TNFB) + 252G/A gene polymorphism, known to be related to autoimmunity, in immune thrombocytopenia (ITP) patients. We also aimed to investigate the association between TNFB + 252G/A polymorphism and susceptibility to develop persistent/chronic ITP. METHODS: One hundred pediatric ITP patients, as well as 50 age- and sex-matched healthy Egyptian subjects, were included. Genotyping of TNF-ß gene (G252A) was done using the PCR-RFLP method. RESULTS: TNFB allele B2 frequency was (64%, 64/100) in controls, (69%, 138/200) in ITP patients, while the frequency of the variant allele B1 was 36% (36/100) in controls, (31%, 62/200) in ITP patients. TNFB genotype frequency in ITP patients showed equal frequency for B2B2 and B1B2 genotypes, (46%, 46/100), while B1B1 frequency was 8% (8/100). Among controls, frequencies of B2B2, B1B2 and B1B1 genotypes were 36% (18/50), 56% (28/50), and 8% (4/50), respectively. Odds ratio for the risk of developing ITP revealed no statistically significant risk, associated with any allele or genotype. No association was encountered between different genotypes and age, hematological parameters, gender, stage of the disease or response to treatment. DISCUSSION: Comparison between ITP patients and controls as regards TNFB allele and genotype frequencies showed no statistically significant difference. No increased risk for developing ITP was associated with any allele/genotype. CONCLUSION: The risk of developing ITP was not related to the studied polymorphism.

CD200 expression in B-cell chronic lymphoproliferative disorders.

BACKGROUND: Flow cytometry immunophenotyping (FCIP) is used for rapid, specific diagnosis of B-chronic lymphoproliferative disorders (BCLPDs). However, cases may deviate from the typical immunophenotype; therefore, there is a need for adding new marker(s) for differentiating BCLPDs.Lately, few researches highlighted CD200 expression in some BCLPDs. Our aim was to evaluate CD200 expression in different BCLPDs and whether adding CD200 to BCLPD-FCIP routine panels could improve the ability of their differential diagnosis. METHODS: We evaluated CD200 expression in 49 BCLPD patients and 26 age- and sex-matched control subjects. Flow cytometry immunophenotyping first panel included CD5, CD19, sIg, CD23, CD22, CD79b, and FMC7; for BCLPDs other than chronic lymphocytic leukemia (CLL) and mantle cell lymphoma, CD11c, CD103, CD25, and CD10 were evaluated. RESULTS: Using tricolor FCIP, CD200 showed high bright expression on CD5/19-positive clone in all B-CLL patients (100%), with a mean of 94% (SD, 11%); in the 2 cases of hairy cell leukemia, CD200 was brightly expressed on 96% and 99% of cells. In all other BCLPDs including mantle cell lymphoma, follicular lymphoma and splenic marginal zone lymphoma, CD200 expression (on CD19/22-positive cells) was less than 20% with a mean of 10% (SD, 8%) and a dim pattern. CD200 expression was significantly higher in CLL compared with non-Hodgkin lymphoma groups (P < 0.001). CONCLUSIONS: Evaluating CD200 expression has a great impact on accurate BCLPDs diagnosis and could be added to the BCLPD routine panels. The high expression of CD200 in B-cell CLL and hairy cell leukemia could open the option for targeted immune (anti-CD200) therapy.