Abstract
The response of peripheral blood lymphocytes to stimulation by mitogens such as phytohaemagglutinin (PHA) is commonly depressed in both rheumatoid arthritis and iron deficiency, and as many rheumatoid patients are anaemic with evidence of abnormal iron metabolism it is possible that the same mechanism underlies the observed suppression in both conditions. In the present study the mitogenic response to PHA of lymphocytes from three rheumatoid patients, who were also iron deficient, and two healthy controls has been shown to be significantly less in iron deficient than iron containing media (p less than 0.001). In addition, iron deficient sera from these patients reduced the PHA induced proliferation of lymphocytes from a normal subject (p less than 0.01), an effect which was prevented by prior addition of iron to these serum samples. In iron containing media lymphocytes from five patients and two controls showed no difference in their response to PHA for both the minimum mitogen concentration which enhanced transformation and the peak [3H]thymidine uptake; but patients' lymphocytes showed significantly less response to PHA concentrations of 5 and 10 mg/l (p less than 0.02), resulting in a reduction in the area under the dose response curves up to 20 mg/l (p less than 0.05). These findings show both that iron deficient sera can impair PHA induced lymphocyte transformation and that lymphocytes from iron deficient rheumatoid patients have impaired responsiveness to PHA. Iron is known to be required intracellularly for the enzyme ribonucleotide reductase, which is important for DNA synthesis, and reduced activity of this enzyme could explain these observed effects.