[Availability of the 3rd platelet factor in healthy children]

In 34 healthy children at school-age the availability of the 3rd platelet factor was determined using plasma of mean concentrations of 100 000 and 342 000 platelets/mm3. The concentration of 100 000 platelets/mm3 gives very approximate results to those obtained with the higher concentration. Both curves of availability of this factor showed many features in common. The highest activity of the factor was observed from 0 to 10--15 min. of the incubation and after this peak it decreased gradually. The authors present and discuss the types of curves indicating physiological values.