Investigation of tissue factor mRNA levels in human platelets using real-time PCR
Tissue factor (TF), a 47 kDa glycoprotein, is the initiator of the extrinsic pathway of blood coagulation and consequently of the upmost importance when damage to blood vessel occurs. The source of TF in circulation has been investigated. However, the source of TF is still not clear. One theory is that platelets express and increases the expression of TF after stimulation and the aim of our report was to investigate whether platelets really are a source for TF in circulation.Using specific primers for TF mRNA, platelets in plasma from healthy volunteers and from patients suffering from cardiac infarction were analyzed by using real-time polymerase chain reaction (PCR). Gel electrophoresis was performed after amplification of TF mRNA to verify the results.The samples were negative for TF when using real-time PCR and the few positive all had cycle threshold (Ct) values above 35. The contamination by monocytes was analyzed by using real-time PCR, with primers for CD14 and showed low amounts.After analysis, our conclusion was that platelets do not express TF. Although some samples had positive real-time PCR, the Ct values were all above 35, meaning they had very few transcripts in the initial samples and that the biological importance is uncertain. Since contamination of CD14 positive cells were found in most samples it can?t be ruled out that the origin of the positive TF mRNA is from monocytes.