α4β1+ and α4β7+ CD4+ T cell numbers increase and CLA+ CD4+ T cell numbers decrease in systemic sclerosis

We studied the expression of adhesion molecules affecting recirculation and homing on peripheral blood CD4⁺ T cells of patients with systemic sclerosis (SSc), in order to evaluate whether the distribution of tissue targeted subsets could reflect the participation of internal organs or the extent of cutaneous involvement [i.e. limited cutaneous (lc) and diffuse cutaneous (dc)]. Peripheral blood mononuclear cells (PBMC) from 51 patients with SSc and 19 sex- and age-matched controls were investigated by cytofluorimetric analysis for lymphocyte subpopulations carrying the following surface molecules: CD3, CD4, CLA, α4β7 and α4β1. Standard routine biochemistry and clinical examinations were also performed in all patients. We found that both α4β1⁺ and α4β7⁺ cells within the CD4⁺ T cell population were significantly increased, while CLA⁺ CD4⁺ T cells were significantly reduced in SSc, compared to healthy donors. Significantly lower absolute numbers of α4β7⁺ cells were found in lc- compared to dc-SSc. Patients with oesophageal involvement had high numbers of α4β7⁺ cells, while those with nephritis also showed low levels of CLA⁺ cells. Lung involvement was related directly to α4β1⁺ cell numbers and inversely to α4β7⁺ CD4 cell numbers. Taken together, our findings demonstrate that distinct CD4⁺ T cell populations with selective homing properties show changes from normal distribution in SSc, and such changes are related to clinical expression and organ involvement in the course of the disease.