Increased surface receptor Fas (CD95) levels on CD4+ lymphocytes in patients with primary intestinal lymphangiectasia

Objective. Exudative enteropathy secondary to primary intestinal lymphangiectasia (PIL) is characterized by lymphopenia, hypogammaglobulinemia and hypoalbuminemia resulting from leakage of lymph fluid into the intestinal tract. The objective of this study was to better characterize the lymphopenia of PIL-confirmed patients. Material and methods. T-cell markers and T-cell proliferation/capacities (differentiation, activation and death) were analyzed for phenotype in 9 patients (6 F, 3 M, aged from 18 to 72 years). Results. Mean counts of CD4 and CD8 subsets were significantly decreased, 174±123/µl and 134±77/µl compared with controls, 858±260/µl and 482±164/µl, respectively (p<0.0001). Significant depletion of naïve (CD45RA⁺ CD62L⁺) CD4⁺ T cells was noted, with a mean expression of 7±4% compared with controls, 45±1% (p<0.0001). Both CD4⁺ and CD8⁺ T-cell mean subsets were activated as assessed by their proportion expressing the late activation markers HLA-DR, 18±7% and 19±9% compared with controls, 6±3% and 10±6%, respectively (p<0.0001 and p<0.01). The mean expression of CD95/Fas on CD4⁺ T cells was significantly higher in patients than in controls, 83±16% versus 45±13% (p<0.0001). No major abnormality of T-cell proliferation/capacities was observed. Conclusions. Our results suggest that the T-cell loss in PIL patients is probably due to various mechanisms including enteric lymphocytes loss and activation of residual T cells, leading to death. Moreover, this loss is not compensated by a sufficient increase in T-cell thymic production.