Some observations on the blood serotonin levels in rheumatoid arthritis with a study of platelet serotonin absorption

Abstract

Using spectrophotofluorimetric methods, the blood platelet and plasma free serotonin levels have been determined in 13 patients with active rheumatoid arthritis and the results compared with the findings from a group of normal subjects. To examine the ability of the platelets to take up serotonin in vitro, the uptake of the amine by platelets incubated at 37° in a serotonin-rich environment was measured. Both the “steady state” saturation capacity and the “percentage” saturation before incubation have been determined. The platelets from patients with active rheumatoid arthritis were shown to be significantly lower in serotonin content than the normal platelets and to be circulating less than 20% “saturated”. The normal platelet serotonin saturation level was between 20% and 38% of the steady state concentration capacity. The findings have been discussed and a number of theoretical concepts have been proposed in an attempt to explain these differences.