Platelet survival and platelet production in systemic lupus erythematosus (SLE)

Platelet survival studies were carried out on 36 patients suffering from SLE. Twelve of them received no therapy, 17 were on corticosteroids (CS), and the remaining 7 received CS and azathioprin (AT). Ten healthy hospital employees served as controls. Only 1 of our SLE patients had thrombocytopenia (platelet count 42 x 10(9)/l). All the remaining 35 patients had venous platelet counts greater than or equal to 120 x 10(9)l. In the control group the average platelet mean life-span (MLS) was 5.8 +/- 0.3 (range 4.0-6.8) days. In the group of untreated SLE patients 3 out of 12 subjects (25%) had a platelet MLS below the lower range for the controls. The mean platelet MLS in the control group did not differ statistically from any of the means of the three groups of SLE patients studied. The lowest mean for platelet MLS (5.2 +/- 0.6 days) was encountered in the group of patients who received no therapy. The means for platelet MLS in the two groups of SLE patients who received immunosuppressive therapy were higher (6.5 +/- 0.4 and 6.6 +/- 0.4 days, respectively) but did not differ statistically from the mean of untreated patients (0.10 > p > 0.05). The mean platelet production rate in the control group (23 +/- 10(10) platelets per day) did not differ from any of the three groups of SLE patients investigated. In the literature it has been proposed that a state of compensated thrombocytolysis is present in most cases of SLE. The results of the present study do not support this hypothesis, however.