Immunoregulation in sarcoidosis

Abstract

The immunoregulatory function of lymphocyte subpopulations was studied in 38 sarcoidosis patients subdivided according to their clinical stage and disease phase. Functions studied included the percentage and absolute numbers of T G and T M lymphocytes and their ability to help and suppress the PWM-induced B-cell differentiation of normal allogenic and autologous B cells. The percentage of T G cells was increased in both active and inactive sarcoidosis, whereas their absolute number was increased only in the active phase of disease. This increase in T G cells was unaffected by pronase treatment and the Fc-IgG receptors were modulated as well as normal T G lymphocytes. The percentage of T M cells appeared statistically reduced only in active sarcoidosis while their absolute number, considering the lymphopenia, appears uniformly reduced in both phases of the disease. Functional analysis in the PWM-induced plasma cell generation assay revealed that T G sarcoid lymphocytes retain the property of suppressing B-cell differentiation, suggesting a quantitative imbalance without qualitative alterations. Aside from being diminished, the T M cells were not able to provide an optimal intracytoplasmic Ig production thereby supporting the presence of a qualitative deficiency. B sarcoid cells when cocultured with autologous T non-G populations in the presence of a polyclonal activator showed an impairment in plasma cell production; however, B-cell function was almost completely restored when the help was provided by normal T non-G lymphocytes, suggesting that the abnormalities observed in sarcoid patients are entirely related to alterations in the T immunoregulatory functions. The implications of the finding of increased suppressor and diminished helper activity in sarcoidosis patients are discussed.