Lymphocytopenia-associated sarcoidosis: CD4+ T-cell hypo-responsiveness to IL-2 and lectin

Abstract

Despite classical identification of immune response impairment in sarcoidosis, such as anergy to delayed skin tests, the characterization of contributing mechanisms are still uncertain and infectious events complicating the course of the disease are unfrequent. Rarely, additional quantitative T-cell defects are reported in association with the disease. Although mechanisms of lymphocyte disorders are unknown, lymphocytopenia is usually revealed by an opportunistic infection.

We report the case of an 18-year-old man, with pulmonary sarcoidosis, treated by corticoids, who developed cryptococcal meningitis. A CD4+ T-cell defect was simultaneously discovered, which was not influenced by corticoid arrest, persisted following infection resolution and control of sarcoidosis. In vitro experiments were performed in parallel, demonstrating a restricted CD4+ T-cell proliferation hypo-responsiveness to both IL-2 and lectin. In addition, rhIL-2 subcutaneously administrated failed to restore peripheral T-cell count.

A multi-visceral sarcoidosis associated to CD4-lymphocytopenia is rarely reported and highly demonstrative of the related risk for an opportunistic infection development. In context, the absence of lectin and IL-2 effects on in vitro CD4+ T-cell proliferation assays and the inefficiency of in vivo rhIL-2 on T-cell count have been infrequently reported and suggested the presence of a defective intracellular signaling pathway, responsible for T cell defect.