[Cytokines in children with immunodeficiencies].

The underlying immunological defect in humoral immunodeficiency with decreased production of immunoglobulin and normal level of circulating B cells (IgA deficiency, transient hypogammaglobulinemia of infancy, common variable immunodeficiency) remains unknown. There is evidence that B cells maturation and differentiation is regulated by cytokines and hence aberrant cytokine production may be involved in the pathogenesis of these diseases. Among interleukins, IL-1, IL-4, IL-6 and IL-10 may each play a role in regulation of B cell growth. Interferons (IFNs) have been described as having both positive and negative effects on B cell growth. The precise role of tumor necrosis factors (TNF alpha and beta) remains obscure. In the present study the in vitro cytokine production by peripheral blood mononuclear cells (PBMC) from children with different forms of immunodeficiency, in particular with IgA deficiency and transient hypogammaglobulinemia of infancy, was evaluated. In the first stage of the study the release of IL-1, IL-6, IFN and TNF by PBMC was analysed in following groups of patients: transient hypogammaglobulinemia (n = 30), IgA deficiency (n = 29), Bruton's disease (n = 7), decreased proliferative response to mitogenes (n = 10), CD4+ lymphocytopenia (n = 8), CD8+ lymphocytopenia (n = 10). The concurrent control group consisted 52 sex- and age-matched children, in whom no immunological immunological abnormalities were detected. The release of bioactive IL-1, IL-6, IFNs and TNF was measured in the culture supernatants from PBMC stimulated with mitogens for 48 hours. While the release of bioactive IL-1, IL-6, and IFNs was comparable in all studied groups, the secretion of TNF was significantly increased in children with transient hypogammaglobulinemia and IgA deficiency. The next issue was determination of the type of TNF (alpha or beta) involved. The production of other cytokines important for the regulation of B cell function (IL-4, IL-10) was also assessed. Production of TNF alpha, TNF beta and IL-10 was significantly elevated in transient hypogammaglobulinemia. The data from the ELISPOT assay suggested, that in these patients also the number of cells secreting TNF alpha after PHA stimulation was increased. These results indicate, that elevated TNF alpha production was probably due to both an enhanced release and an increased number of circulating secreting cells. As the methods employed in the quantification of cytokine levels in culture supernatants do not allow identification of the cytokine producing cell, the studies on intracellular expression of cytokines were undertaken. The fluorochrome-labelled monoclonal antibodies against the cell surface markers and a given cytokine were used simultaneously to identify the cellular source of cytokine production. The intracellular IL-4 expression in CD4+ lymphocytes from patients with transient hypogammaglobulinemia was comparable to that of control while the number of CD4+ lymphocytes expressing TNF alpha, TNF beta and IFN gamma was elevated. The number of CD14+ cells (monocytes) producing of TNF alpha was comparable to the control. These results suggest that an excessive Th-1 type response may contribute to pathology of this disease. In patients with isolated IgA deficiency the significantly increased release of TNF alpha but not: IL-1, IL-4, IL-6, IL-10 and TNF beta was observed. The proportion of CD4+ lymphocytes that expressed TNF alpha was significantly increased while the number CD14+ cells staining for TNF alpha was unchanged. No changes in the expression of TNF type I and II receptors on PBMC were observed, which suggested that regulatory effects of TNF alpha and beta are associated rather with an increased production of these cytokines than an abnormal receptor expression. Some patients with transient hypogammaglobulinemia were followed-up and the serum level of IgG and production of TNF alpha, TNF beta, and IL-10 by their PBMCs was determined 6 to 12 months after first