Humoral immunodeficiency in T-cell chronic lymphocytic leukemia. An immunologic assessment

Circulating levels of cytokines and soluble cytokine receptors in various T-cell malignancies

BACKGROUND

Cytokines, interleukin (IL)-4, IL-6, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), soluble CD23 (sCD23), and soluble IL-2 receptors (sIL-2R) are mediators of inflammation and immune response. Alterations in immune status of patients with various cancers may result in release of cytokines in circulation. The authors measured the circulating levels of IL-4, IL-6, IFN-gamma, TNF-alpha, sCD23, and sIL-2R from patients with T-cell chronic lymphocytic leukemia (T-CLL), T-cell acute lymphoblastic leukemia (T-ALL) and peripheral T-cell lymphoma (PTCL) to determine their importance in these T-cell disorders.

METHODS

IL-4, IL-6, IFN-gamma, TNF-alpha, sCD23, and sIL-2R levels were measured from the serum samples by enzyme-linked immunosorbent assay or bioassay methods.

RESULTS

IL-4 levels were higher only in T-CLL, whereas, IFN-gamma and sIL-2R levels were higher in T-CLL and T-ALL. However, IL-6, TNF-alpha, and sCD23 levels were higher in PTCL.

CONCLUSIONS

T-cell-derived IL-4 and IFN-gamma in T-CLL may act as an autocrine growth factor for proliferation of neoplastic T-cells. The sIL-2R levels in T-CLL, T-ALL, and PTCL are an indication of the degree of T-cell or immune activation due to concomitant immunologic processes in these disorders. However, IL-6, TNF-alpha, and sCD23 levels may contribute to inflammatory response and provide evidence of monocyte/macrophage, T-cell, or B-cell aberrations in PTCL.

Peripheral T-cell lymphoma with unique immunologic features

BACKGROUND

The autologous mixed lymphocyte reaction (AMLR) is an important immunoregulatory phenomenon in human immune disorders. The authors have determined the phenotype and assessed the response of malignant lymph node T-cells, from histologically and immunologically proven cases of peripheral T-cell lymphoma, in AMLR and allogeneic mixed lymphocyte reaction (MLR) and studied the secretion of lymphokines.

METHODS

The proliferative response, tritiated 3H-thymidine incorporation assay, was used to determine the AMLR and allogeneic MLR of the responding T-cells. An interleukin-2 (IL-2)-dependent T-cell line (CTLL) was used for the production of IL-2 by phytohemagglutinin-stimulated T-cells in a cytotoxic assay. B-cell growth and differentiation factor activity of T-cells was studied by enzyme-linked immunosorbent assay.

RESULTS

The AMLR of malignant lymph node T-cells was increased characteristically in 12 of the 14 lymphoma cases studied; however, that of the blood T-cells was decreased. The allogeneic MLR of the malignant lymph node T-cells and blood-purified T-cells of the eight cases investigated was decreased. Expression or deficiency of CD2 and CD3 antigens on malignant T-cells did not show any difference in the AMLR assay.

CONCLUSIONS

This study demonstrates an important tendency of malignant T-cells from patients with peripheral T-cell lymphoma to proliferate in AMLR. The highly augmented AMLR but deficient allogeneic MLR observed in these malignant T-cells indicate that autologous recognitive events may play an important role in the immunopathogenesis of this human disease.

T-cell chronic lymphocytic leukemia. T-cell function and lymphokine secretion

The leukemic T-cells of the six patients with T-cell chronic lymphocytic leukemia (T-CLL), four with CD4 and CD45R-positive (CD4+ CD45R*) T-CLL and two with CD8 and CD45R-positive (CD8+ CD45R+) T-CLL phenotype were studied for detailed immunologic phenotypic and functional characteristics. The levels of soluble interleukin-2 receptors were elevated significantly in the serum of all four patients with CD4+ CD45R+ T-CLL. Moreover, the CD4+ CD45R+ T-CLL patients' T-cells, after in vitro stimulation with phytohemagglutinin and concanavalin A, expressed elevated percentages of interleukin-2 receptors on cells and secreted high interleukin-2 activity. The B-cell growth factor (BCGF) activity from three patients with CD4+ CD45R+ T-CLL was enhanced, but B-cell differentiation factor (BCDF) activity of the all T-CLL patients was decreased. Reduced BCGF and BCDF activity of the leukemic T-cells was one possible mechanism of hypogammaglobulinemia detected in two patients with T-CLL. All T-CLL patients' leukemic T-cells had diminished immunoregulatory functional activity in allogeneic mixed lymphocyte reactions. These observations suggest that leukemic T-cells from T-CLL patients have many immunologic functional defects that may be important in their proliferative potential.