High CD6 and low chemokine receptor expression on peripheral blood lymphocytes correlates with MRI gadolinium enhancement in MS

•CD6 mRNA correlates with the number and size of Gd+ lesions.•Gd+ lesion correlates with increased CD6 and decreased CCRs expression on PB T cells.•Co-expression of CD6 with CCR1 and CCR5 predisposes T cells for migration into CSF.

Correlation between gadolinium-enhancing [Gd(+)] lesions on MRI and expression of CD6 molecules and a group of chemokine receptors on peripheral blood (PB) and cerebrospinal fluid (CSF) immune cells was measured in multiple sclerosis (MS) patients. Twenty remitting–relapsing MS patients with (n = 10) and without (n = 10) Gd(+) lesions entered the study. mRNA and surface expression of CD6 and CCR1, CCR2, CCR3 and CCR5 was measured by immunostaining and flow cytometry. Expression of mRNA and surface staining for CD6 in PB T lymphocytes was increased in Gd(+) compared to Gd(–) patients (p < 0.01; p < 0.05, respectively). CD6 mRNA correlated with the number and size of Gd(+) lesions (r = 0.67, and r = 0.65 respectively). mRNA and surface expression for CCR1, CCR2, and CCR3 in PB cells was lower in Gd(+) compared to Gd(–) MS patients (p < 0.05, p < 0.05). The frequency of cells co-expressing CD6 with CCR1 and CCR5 was low in PB T lymphocytes and high in CSF (p < 0.05, p < 0.05). These results suggest that Gd(+) correlates with increased expression of CD6 and decreased expression of chemokine receptors on PB T lymphocytes. Co-expression of CD6 with CCR1 and CCR5 predisposes cells for transmigration into CSF.