[Biological properties and therapeutic use of interleukin 2 (IL-2)]. / Wlasciwosci biologiczne i zastosowanie lecznicze interleukiny 2 (IL-2).

A cytokine produced by the subpopulation of activated helper lymphocytes T has been called interleukin-2 (IL-2). The obtaining of recombinant cytokine has facilitated the study of its biological properties and its application in the treatment of certain neoplastic and infectious diseases. IL-2 affects the target cells by means of a receptor of great affinity consisting of three independent chains: alpha, beta, gamma. The cytokine is the most important growth factor of lymphocytes T, conditioning their clonal expansion. Antigen stimulation is the condition for the expression of IL-2 does not, however, affect resting lymphocytes T. The expression of the receptor for this cytokine on NK cells is, however, continuous in character but only a very small percentage of these cells has receptors of great affinity. IL-2 plays a great role in adoptive immunotherapy consisting in intravenous administration of cells with cytotoxic properties. Cells obtained from peripheral blood and grown in vitro are called LAK cells (lymphocyte activated killer cells), while cells obtained from neoplasms and grown in similar conditions are named TIL cells (tumor infiltrated lymphocytes). LAK and TIL cells reveal a similar antineoplastic activity in vivo. At present, however, recombinant IL-2 alone is used more often, either intravenously or subcutaneously. The cytokine is effective in the treatment of patients with disseminate cancer of the kidney and melanoma, and in adjuvant therapy of acute myeloid leukemia. Attempts have been made to apply it in the treatment of AIDS and leprosy. The toxic effect of IL-2 depends on the dose and the mode of administration. In the majority of patients parainfluenza symptoms appear. Most undesirable effects are connected with multisystemic syndrome of capillary vessels hyperpermeability leading to the increased fluid retention into extravascular spaces, oedema, hypotonia and oliguria.

Defining protective responses to pathogens: cytokine profiles in leprosy lesions.

The immunological mechanisms required to engender resistance have been defined in few infectious diseases of man, and the role of specific cytokines is unclear. Leprosy presents clinically as a spectrum in which resistance correlates with cell-mediated immunity to the pathogen. To assess in situ cytokine patterns, messenger RNA extracted from leprosy skin biopsy specimens was amplified by the polymerase chain reaction with 14 cytokine-specific primers. In lesions of the resistant form of the disease, messenger RNAs coding for interleukin-2 and interferon-gamma were most evident. In contrast, messenger RNAs for interleukin-4, interleukin-5, and interleukin-10 predominated in the multibacillary form. Thus, resistance and susceptibility were correlated with distinct patterns of cytokine production.

Defective cell-mediated immunity in leprosy: failure of T cells from lepromatous leprosy patients to respond to Mycobacterium leprae is associated with defective expression of interleukin 2 receptors and is not reconstituted by interleukin 2.

Patients with lepromatous leprosy (LL) but not borderline tuberculoid leprosy (BT) have defective cell-mediated immune responses to Mycobacterium leprae, despite normal responses to other stimuli, as judged by in vivo skin testing and in vitro lymphocyte transformation. To investigate the basis of the immune defect in LL patients, we studied the ability of patient mononuclear leukocytes to produce interleukin 1 (IL 1) and interleukin 2 (IL 2) upon stimulation with M. leprae, and determined the ability of exogenous IL 1 and IL 2 to reconstitute the LL patient response to this antigen in vitro. Equal numbers of adherent non-T cells from LL and BT patients produced similar amounts of IL 1 upon challenge with M. leprae, and addition of IL 1 to the culture medium failed to reconstitute the response of lymphocytes from LL patients to M. leprae. On the other hand, T cells of LL patients failed to express receptors for IL 2 or to produce IL 2 in response to M. leprae, whereas similarly treated T cells of BT patients both expressed IL 2 receptors and produced IL 2. Finally, recombinant human IL 2 purified to homogeneity as well as crude supernatants of mitogen-activated lymphocytes failed to reconstitute the response of LL patients to M. leprae. These results suggest that T cells of LL patients fail to respond to M. leprae despite an ability to produce IL 1 and that their failure to express receptors for IL 2 may explain both defective proliferation and the failure of exogenous IL 2 to reconstitute the response.