Giovanni Boccoli

Primary hypothyroidism associated with interleukin-2 and interferon alpha-2 therapy of melanoma and renal carcinoma.

Four patients out of twenty with renal cancer and melanoma undergoing cancer immunotherapy with interleukin 2 (IL-2) and interferon alpha-2 (IFN-alpha 2) had laboratory evidence of hypothyroidism starting at cycle three to six, with a decline in serum thyroxine below normal and, in three cases, a rise in serum thyrotropin and thyroglobulin. One hypothyroid patient had elevated serum antimicrosomal antibody titres before the start of treatment and two others responded similarly during therapy. Three of the sixteen euthyroid patients also developed elevated titres of this antibody. Partial or complete remission was observed in seven of the patients--three of the four with hypothyroidism showed tumour regression. Thus IL-2 and IFN-alpha 2 can cause hypothyroidism, presumably via induction or exacerbation of autoimmune thyroid reactions. The occurrence of hypothyroidism may be mediated by high-dose IL-2 (rather than by LAK cell therapy as previously suggested) and potentiated by IFN-alpha 2.

Three new class I HLA alleles: structure of mRNAs and alternative mechanisms of processing

Sixteen HLA class I clones have been isolated from a SV40-transformed human fibroblast line (GM637) cDNA library. The clones, characterized by hybridization to ABC locus-specific probes and sequence analysis, correspond to transcripts from four different class I genes: A2, A10, Cw4, and Cw6 (or Cw7), as implied by cell typing. Only the A2 sequence was known. The nucleotide and deduced amino acid sequence of the new alleles are reported here, and their structural features are discussed. Two independent cDNAs of A2 specificity display an unusual polyadenylation site located 100 by upstream from the canonical one. Moreover, two cDNAs pertaining to the same C allele display two alternative mechanisms of splicing, which cause either presence or absence in mature transcripts of the transmembrane exon 5 sequence. Transcripts missing this region are predicted to synthesize a nonmembrane-bound, secreted antigen. A soluble protein, specifically reacting with class I-specific HLA antibodies, is found in the supernatant of the GM637 cells. The significance of HLA class I transcripts generated by differential processing is discussed.

Interleukin-2 bolus therapy induces immediate and selective disappearance from peripheral blood of all lymphocyte subpopulations displaying natural killer activity: role of cell adhesion to endothelium.

As early as 10-15 min after the start of a 30 min interleukin-2 (IL-2) infusion, a rapid, virtually complete disappearance of all natural killer (NK) lymphocyte subpopulations (including both CD3- CD56+ and CD3+ CD56+ cells with either alpha/beta or gamma/delta T-cell receptor) was observed from peripheral blood. In contrast, the number of T lymphocytes (CD3+ CD56-) was unmodified for at least 2 h after IL-2 injection. The IL-2-induced, rapid disappearance from peripheral blood of NK and NK-like lymphocytes may be related to their massive adherence to the activated endothelium. In this regard, IL-2 infusion caused a very rapid rise of tumour necrosis factor-alpha (TNF-alpha) plasma concentration, whereas other cytokines, such as interferon-gamma (IFN-gamma), were induced only at later times. In vitro experiments indicated that IL-2, either alone or better combined with TNF-alpha, exerts a rapid and selective stimulatory effect on NK adhesion to endothelial cells. On the basis of these findings, we suggest that the activation of NK lymphocytes induced by IL-2, alone or combined with TNF-alpha, plays a key role in mediating the massive and selective adherence of NK and NK-like cells following IL-2 bolus infusion.

IL-2 induces the release of secondary cytokines which stimulate the cytotoxic activity of either NK or CD8(+) lymphocytes.

The therapeutic potential of interleukin-2 (IL-2) for the treatment of human cancer has been extensively investigated (cfr. 1). In cell cultures IL-2 activates not only the lymphocytes which mediate MHC-restricted recognition of specific target cells, but also the natural killer (NK) lymphocytes which lyse in vitro particular tumor targets, The lymphokine-activated killer (lAK) cells, obtained by culturing peripheral blood lymphocytes (PBL) with IL-2 (2) exhibit the capacity of lysing a wide range of fresh and cultured malignant cells and virally-transformed normal tissues with minimal destruction of normal cells (2). Clinical trials have shown that significant anti-tumor responses are observed in a minority of patients with disseminated malignancies following infusion of large dosages of 11-2, combined or not with IAK cells (3). However severe toxicity is associated with high-dose IL-2 therapy (3). The administration of IL-2 results in a series of typical modifications of circulating blood cells. Thus IL-2 has a pronounced effects on the number of circulating lymphocytes: lymphopenia develops early after initiation of bolus IL-2 infusion and persists during the entire period of IL-2 administration. Within 24-48 h after discontinuance of IL-2, a marked rebound lymphocytosis develops (4); the level of rebound is doseand schedule-related (4). Furthermore, IL-2 infusion also elicits a series of secondary effects on the hematopoietic system: i) a progressive anemia may develop, which often requires blood transfusion; ii) thrombocytopenia is occasionally monitored; iii) eosinophilia often occurs, particularly after prolonged IL-2 administration (5). Prelimirary studies suggested that these hematological changes were associated with a decline in circulating erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitors (5). In the present study we have investigated the mechanisms responsible for IL-2-induced hematological modifications and the possible role of secondary IL-2-induced cytokines in the activation of cytotoxic lymphocytes.