ORLANDO—Patients with secondary progressive multiple sclerosis (SPMS) have impaired regulation, according to data presented at the Fifth Cooperative Meeting of the Consortium of MS Centers and the Americas Committee for Treatment and Research in MS. Compared with healthy subjects, patients with SPMS have reduced frequencies of Tr1 precursors, Tr1 cells, and nTreg cells. The nTreg cells in patients with SPMS, however, maintain levels of FOXP3 and CD39 similar to those of healthy controls.
Healthy subjects examined with multicolor flow cytometry had greater numbers of inhibitory PD-L1+ and HLA-G+ monocytes than did patients with SPMS, said Lauren W. Collison, PhD, Director of Immunology at Opexa Therapeutics in The Woodlands, Texas. In patients with SPMS, the memory T cell compartment had increased levels of Th17 and decreased numbers of Th2 cells, compared with controls. Controls had higher levels of Th1 cells than of Th17 cells, but the opposite was true for patients with SPMS.
Using an acoustic focusing flow cytometer, Dr. Collison and colleagues characterized peripheral blood mononuclear cells from healthy subjects and patients with SPMS. They analyzed the samples with multicolor flow cytometry using 16 six-color marker panels.
The researchers determined specificity by comparing test molecules to isotype-matched controls or by preincubating test molecules with clonally matched purified blocking monoclonal antibodies. They performed t-test analysis to determine the statistical significance of any difference between means of healthy donors and of patients with SPMS.
The number of regulatory T cells, both adaptive/peripherally generated TR1 cells and natural/thymic derived nTreg cells, was determined in healthy subjects and patients with SPMS. The mean percentage of TR1 precursor cells (CD4+CD18brightCD49b+) and TR1 cells (CD4+CD45RA-LAG3+CD49b+) was significantly greater among healthy subjects, when compared to patients with SPMS. Non-TR1 cell numbers (CD8+CD18brightCD49b+ or CD4+CD45RA-LAG3+CD49b+) were similar for both groups.
Healthy donors also trended toward a greater frequency of CD4+ nTregs. A greater percentage of CD4+ T cells were FOXP3 nTreg cells in controls, compared with patients with SPMS. The mean fluorescence intensity of FOXP3 nTreg cells was similar for both subject groups.
Similarly, a greater percentage of CD4+ T cells in healthy donors was CD25bright nTreg cells, when compared with patients with SPMS. However, among CD4+ nTreg cells, CD39 expression was comparable in healthy donors and subjects with SPMS.
—Erik Greb
Senior Associate Editor