Decreased NK activity in hairy cell leukemia (HCL): an analysis at the cellular level

Splenic metastasis in hairy cell leukemia

BACKGROUND

Splenic metastasis is uncommon and usually occurs in the setting of widespread visceral metastasis. Splenic metastasis as an initial manifestation of disease and sole site of metastasis has not been reported previously.

METHODS

The authors describe a patient with hairy cell leukemia (HCL) with the unexpected finding of metastatic adenocarcinoma in the spleen. Direct inspection at the time of laparotomy and subsequent radiographic studies did not show a primary or additional metastatic tumor. Eventually, he manifested evidence of pulmonary and hepatic metastases and died with fungal sepsis.

RESULTS

The splenectomy specimen showed HCL and metastatic adenocarcinoma. Immunohistochemical studies showed adenocarcinoma with diffuse cytoplasmic staining for prostate-specific antigen and focally positive results with prostatic acid phosphatase antigen. Postmortem examination 9 months later showed HCL and widespread metastatic adenocarcinoma. No primary tumor was identified, and multiple tissue blocks of the prostate had negative findings for tumor.

CONCLUSIONS

The immunohistologic features of the metastatic adenocarcinoma were interpreted as prostatic in origin. The pattern of isolated metastatic disease in the absence of primary tumor appears to represent another possible atypical disease presentation of prostatic cancer. Hairy cell-induced structural and immunologic alterations within the splenic microenvironment may have contributed to this unique clinical presentation.

Agar capillary clonogenic microassays for cellular immunocytotoxic activities in human leukaemia and lymphoma

Current concepts of immunotherapeutic approaches in leukemias and lymphomas using activated cytotoxic lymphocytes and macrophages are briefly reviewed. Defective cellular immunocytotoxic activities and effects of interleukins and chemotherapeutic drugs thereupon are discussed. In vitro assays to measure lymphokine-activated killer (LAK) and natural killer (NK) cell activities suffer from various problems, depending on the quality of the endpoints. Our clonogenic microassay for LAK cell activity, using agar-containing glass capillaries, avoids some of the potential artifacts and offers several advantages that are discussed. As an example the stimulatory effect of low mafosfamide concentrations on the LAK cell activity versus K562 human myeloid leukemia cells is demonstrated. Thus, our clonogenic LAK microassay provides a valid tool for preclinical screening of immunomodulatory agents.

Natural killer cell function and malignant cell phenotype in hairy cell leukaemia

We have followed for 33 months the changes that occurred in natural killer (NK) cell numbers and activity in a patient (A) with hairy cell leukaemia (HCL), using a single cell assay and a microcytotoxicity assay. The composition of the peripheral blood mononuclear cell population and malignant cell phenotype were also analysed. During this period he received treatment with interferon and his grossly enlarged spleen was removed. Four further patients were also studied, two were splenectomized and all had received treatment with interferon. In four of the five patients studied there was an apparent link between low NK activity and presence of a tumour-infiltrated spleen, and in the fifth patient, who was aleukemic and had no splenomegaly, NK function was related to disease activity. There was no correlation between NK activity and the number of target binding (TB) cells in these five patients. IFN had little direct effect on overall NK activity, but the proportion of killing cells among TB cells was increased. Three patients showed binding of several cells to a single target. Further analysis revealed that in the patients most of the TB cells were not CD56-positive NK cells, in contrast to TB cells from normal subjects. In patient A a large proportion (84%) of TB cells were identified as malignant cells and in patient E 15% of TB cells were malignant cells. The phenotype of the malignant cells was: CD19+, HLA-DR+ and CD25(Tac)+, except for patient A. In this patient the hairy cells were positive for the NK marker CD56 as well as the monocyte marker CD14. Furthermore, a change occurred in phenotype as only later samples carried CD25. It is concluded that the level of NK function correlates closely with disease activity in HCL and that competitive target cell binding by malignant cells may be one cause of depressed NK-cell function in hairy cell leukaemia.

Hairy cell leukaemia: observations on natural killer activity in different clinical stages of the disease

Follow-up studies of natural killer (NK) cells, NK activity and antibody dependent cellular cytotoxicity (ADCC) in the course of hairy cell leukaemia (HCL) were carried out in a series of patients affected by the disease. NK activity against K562 targets was found to be high in all the patients with non-symptomatic stable disease. On the other hand, absent or extremely low NK activity was found only in patients with symptomatic progressive disease. NK activity determined in the transitional stages showed values between these two extremes. Antibody dependent cellular cytotoxicity (ADCC) was less closely correlated with the clinical stage than NK activity. Our findings suggest that investigation of in vitro NK cell cytotoxicity might serve as a useful adjunct in determining clinical stage in HCL.

Clinical response of hairy-cell leukaemia to interferon-alpha: results of an Australian study

Twelve patients with documented, progressive hairy-cell leukaemia were treated with human lymphoblastoid interferon-alpha. All patients initially received a three-month course of interferon-alpha (3 x 10(6) U each day) which resulted in two complete remissions and 10 partial remissions. All eight patients who were dependent upon packed red-cell transfusions became independent of them and the three patients with the most severe, pretreatment pancytopenia also became independent of platelet transfusions. The histological appearance of the bone marrow improved in all patients; in three patients, a complete resolution of the leukaemic infiltrate was recorded. Adverse reactions occurred in 10 patients, but these were mild and did not interrupt treatment in seven patients. Moderate reactions that required a temporary reduction in the dose of interferon-alpha were seen in three patients. Ten patients subsequently received maintenance therapy with interferon-alpha (3 x 10(6) U, three times a week). A haematological improvement continued to be seen in all patients, and the results, with a minimum of one year of follow-up, are presented.