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In this study we investigated the serological levels of the soluble form of the CD8 molecule (s-CD8) in 97 human immunodeficiency virus (HIV) seropositive patients. The control groups included 20 normal heterosexual subjects and 19 healthy seronegative subjects belonging to risk groups for AIDS. Our results show that patients with HIV infection have significantly higher levels of s-CD8 U/ml than the control groups. When the patients were further subdivided according to the Centers for Disease Control (CDC) classification, s-CD8 U/ml values were consistently increased in all HIV patients, irrespective of the CDC stages. No statistically significant correlation was found between the serological levels of s-CD8/ml and the absolute numbers of CD8 lymphocytes/mm3, in both HIV seropositive patients and control groups. Since in the more advanced stages of HIV infection (IV-A, IV-C1) the decrease in the absolute number of CD8+ cells was not followed by a decrease in s-CD8 levels, it is conceivable that an increased release and/or shedding of s-CD8 per cell might occur in these patients. In fact, when the results were expressed as s-CD8 units per CD8 positive cell (s-CD8/absolute number of CD8), the levels of s-CD8/cell were higher in patients belonging to the IV-A and IV-C1 CDC groups (1.94 U/cell +/- 0.33 and 3.39 U/cell +/- 0.5, respectively) compared to normal controls (P less than 0.001), HIV seronegative subjects at risk for AIDS (P less than 0.001), and the other patients' groups (II and III CDC groups, respectively, P less than 0.001 and P less than 0.001). The evidence herein provided that in patients with HIV infection s-CD8 levels are increased suggests a possible pathogenetic role of the cells involved in the release of this molecule.

Proliferating cells have been immunophenotypically characterized in lymph node and bronchoalveolar lavage (BAL) samples obtained from patients with active and inactive sarcoidosis with the cell-cycle-related antigen Ki67. Ki67 monoclonal antibody was used by combined immunohistochemical methods together with antibodies recognizing macrophage- and T-cell-subset-related antigens using avidin-biotin peroxidase (ABC) and alkaline phosphatase-anti-alkaline phosphatase (APAAP) systems. Many proliferating Ki67+ cells were found in affected mediastinal lymph nodes. These cells were mainly located around granulomas and exhibited phenotypical markers of helper/inducer T cells (CD3+, CD4+). Ki67+ macrophages could not be detected in the same lesions with this technique. A different picture was found in BAL preparations where proportions of both T lymphocytes and macrophages were Ki67+. The presence of replicating lymphocytes could be correlated to disease activity, whereas the proportions of Ki67+ macrophages did not show significant differences between active and inactive disease. Interleukin-1 (IL-1) expression was investigated in the same samples with a specific antiserum. Epithelioid macrophages in granulomas and BAL macrophages in all cases exhibited cytoplasmic staining revealing an activated status. Interestingly, giant cells in granulomas were mainly devoid of IL-1 immunoreactivity. These studies support the concept that activated cells at different sites of ongoing inflammation play a central role in the mechanisms accounting for granuloma formation.

We describe a patient with acute lymphoblastic leukaemia whose blasts co-expressed immature T-cell markers and nearly the entire phenotypic repertoire of NK cells. The T-cell nature of the proliferating blasts was proven by the demonstration of the rearrangement for the beta-chain of the T-cell antigen receptor. Although an abnormal phenotypic expression related to the neoplastic proliferation cannot be formally excluded, it is possible that the cells in this patient may represent the clonal expansion of a normal subpopulation of T-cell lineage NK-related cells frozen at an early stage of differentiation. These features provide arguments for discussing the controversial issue of the ontogeny of NK cells and their relationship to the T-cell lineage.

In the current study, we investigated the cytotoxic ability of peripheral blood mononuclear cells (PBMC) recovered from patients with acute nonlymphoblastic leukemia (ANLL) in complete remission (CR) against natural killer (NK)-sensitive, NK-resistant, autologous and allogeneic leukemic target cells taken at diagnosis. Our purpose was to define the role played by cytotoxic mechanisms in the control of leukemic cell growth in ANLL. Experiments were carried out at resting conditions and after in vitro activation with recombinant interleukin-2 (rIL-2) and anti-CD3 monoclonal antibody (moAb). At resting conditions, PBMC recovered from ANLL patients displayed a NK function that was not significantly different from controls (mean +/- standard error of the mean [SEM]: 21.9% +/- 3.9% versus control values of 27.5% +/- 2.9%; the P value was not significant [NS]), but they were unable to show cytotoxic activity against autologous and allogeneic leukemic cells. After in vitro boosting with rIL-2, PBMC were able to generate lymphokine activated killer (LAK) cells, as demonstrated by an increased killing of NK-resistant Daudi targets (16.3% +/- 2.7%). Although LAK activity was quantitatively lower than in control subjects (mean +/- SEM: 16.3% +/- 2.7% versus control values of 79.8% +/- 3.1%; P less than 0.001), it still exerted a cytotoxic effect against autologous and allogeneic leukemic cells. Similar results were obtained when anti-CD3 moAb was used as a stimulus in vitro. Our data suggest that nonspecific cytotoxic cells may be triggered to exert an in vitro cytotoxic effect on leukemic cells, which could possibly play a key role in vivo in the control of leukemic cell growth regulation.

The frequency of cells reactive with anti-Tac monoclonal antibody (MoAb), which recognizes the interleukin-2 (IL-2) receptor, has been evaluated in cell suspensions from peripheral blood and bronchoalveolar lavage (BAL), and in frozen sections from involved tissues in 18 patients with active sarcoidosis. Peripheral blood lymphocytes of sarcoid patients do not bear Tac determinant and reduced numbers of Tac+ cells are inducible following PHA stimulation. On the other hand, significant numbers of lymphocytes reactive with anti-TacMoAb are present in the cells obtained from the BAL and a number of Tac+ cells infiltrate the lung, lymph node and conjunctiva. The finding of Tac+ cells in the BAL fluid and in other organs in patients with sarcoidosis provides evidence that some T cells in these involved tissues have the characteristics of IL-2 responder cells and thus the potential to absorb IL-2, supporting the hypothesis that T lymphocytes replicate in situ at sites of disease activity.

A long term follow-up study has been undertaken in 33 patients with acute non-lymphoblastic leukaemia (ANLL) in order to establish whether a correlation exists between the clinical course and the immunologic pattern of lymphoid subpopulations. Peripheral blood lymphoid cells have been investigated longitudinally (each 1 to 4 months) during complete remission (CR), by morphologic, phenotypic and functional analyses. Particular attention has been paid to the evaluation of the natural killer (NK) cell compartment, by the detection of cells expressing an NK-related phenotype and by NK in vitro assay. Among the patients so far evaluable, 20 relapsed (R) and 10 are long survivors in CR 'off therapy' (LS). The most relevant finding was represented by statistically higher values of NK activity observed in LS vs. R patients (P less than 0.01). The removal of adherent cells before the NK assay, performed to investigate the possible inhibitory effect on NK function played by the macrophage component, abolished this difference, due to a selective increase of NK function in the R group. The longitudinal study revealed that NK activity tended to decrease in individual patients who subsequently relapsed. These data suggest a possible role of NK cells in the relapse control of ANLL, although it cannot be excluded that the low level of NK activity observed in the R group is the result of impending relapse rather than its cause.

To elucidate the mechanisms of alpha-interferon's (alpha-INF) therapeutic effect on clinical and laboratory findings in hairy cell leukemia, we sequentially monitored different immunologic parameters in three patients treated with recombinant alpha-INF. The most evident effect of this treatment on the immune system was the recovery of natural killer (NK) cell in vitro activity of peripheral blood lymphocytes, which was severely impaired before therapy. In particular, NK function began to improve after 3 months, and a complete recovery was obtained after 6 months in all cases. This increase parallels the improvement in clinical and laboratory findings.