Blood levels of three types of immune cells — neutrophils, lymphocytes, and monocytes — may be associated with digital ulcers and disease severity in systemic sclerosis, researchers report.
Their study, “Association of simple hematological parameters with disease manifestations, activity, and severity in patients with systemic sclerosis,” was published in the journal Clinical Rheumatology.
Systemic sclerosis is an autoimmune disease that affects small blood vessels and causes fibrosis (thickening) of skin and internal organs. Abnormal immune responses to tissue damage contribute to systemic sclerosis. Therefore, assessing the levels of immune cells may potentially reflect the degree of inflammation in this patient population.
Researchers at Ankara University in Turkey set out to investigate the possible association between levels of certain immune cells and disease symptoms, activity, and severity in systemic sclerosis patients. Blood tests measured the neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, mean platelet volume, and red cell distribution width.
In total, 69 systemic sclerosis patients (seven men and 62 women, mean age of 53.4 years) and 50 healthy volunteers had their venous blood tested for the proportion of red blood cells, platelets (cells that help with clotting), and three subtypes of white blood cells — neutrophils, lymphocytes, and monocytes — that help the body fight infections and protect it from foreign microorganisms.
The extent of skin fibrosis, and disease severity and activity were also assessed using clinically validated measures.
The researchers found the neutrophil count was significantly higher, while the level of lymphocytes was significantly lower in the patient group. As a result, systemic sclerosis patients had higher neutrophil-to-lymphocyte ratio values, and these were positively correlated with disease activity, skin fibrosis, and C-reactive protein levels (high concentrations of C-reactive protein are indicative of inflammation within the body).
Neutrophil-to-lymphocyte ratio was also found to be increased in patients with digital ulcers — a common symptom of systemic sclerosis — suggesting that neutrophil and lymphocyte levels might be a marker of these ulcers.
Although the monocyte count was not different between the two groups, the monocyte-to-lymphocyte ratio was higher in the patients, which could be due to their low lymphocyte count. The monocyte-to-lymphocyte ratio was associated with digital ulcers and cardiac changes. It was also positively correlated with skin fibrosis, and disease activity and severity.
Unlike these immune-cell ratios, C-reactive protein was found not to be related to skin thickening, or disease symptoms or severity.
Interestingly, monocyte levels independently predicted higher disease activity and severity.
No differences were found in the mean number of platelets between patients and controls.
“Globally available and inexpensive hematological tests, particularly the [neutrophil-to-lymphocyte ratio] and [monocyte-to-lymphocyte ratio], may be associated with vascular and cutaneous manifestations as well as disease activity and severity in [systemic sclerosis],” the researchers stated.