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Biomedical subjects

H W Pees

Publications and source records attributed to H W Pees.

24 records · Page 2Linked to original sources
PubMed1980

[The influence on PHA-stimulation by inhibition of prostaglandin synthesis in vitro in patients with Hodgkin's disease (author's transl)].

Adherent mononuclear cells may have suppressor functions mediated by prostaglandins (PG). In the present study we tested a large number of normal donors and patients with Hodgkin's disease (HD) using PHA and the prostaglandin inhibitor indomethacin (IM). Stimulation of mononuclear cells from 24 healthy volunteers with PHA led to a mean response of 27 833 cpm; addition of IM caused a 32% increase of 3H-thymidine incorporation. The corresponding values for 30 patients with HD stages IIA-IVB were 14,064 cpm and 70% increase with IM. The effect of the drug was much more pronounced during relapse or progression than in untreated patients. There was an inverse relationship between PHA-response and per cent increase both in normal donors and Hodgkin patients. Depletion of adherent cells using Sephadex G-10 columns abolished the effect of IM completely, but PHA-stimulation was also slightly depressed. Our failure to observe an increase of the mitogen response after removal of monocytes may be related to the technique employed. However, an additional defect of Hodgkin lymphocytes must be considered.

Adolescent↗
PubMed1979

Cytotoxic immune response of meningioma patients towards allogeneic and autologous tumour cells before and after surgery.

Cell-mediated cytotoxicity (CTX) of meningioma patients towards meningioma cells and fibroblasts was studied in vitro before and after surgery, using the 3H-proline microcytotoxicity test. When incubated with allogeneic target cells before surgery, lymphocytes from three out of seven donors showed a specific destruction of meningioma tissue, and two were cytotoxic on both types of targets. Five patients were tested against their own tumour and against skin fibroblasts; this was feasible by keeping their lymphocytes frozen in liquid nitrogen until their target cells grew as suitable monolayers in vitro. Three patients showed a specific cytotoxic response. After excision of the tumour a gradual loss of this reactivity was observed in both allogeneic and autologous systems. Sera of three patients, whose lymphocytes were not reactive against their own tumour, induced antibody-dependent cellular cytotoxicity (ADCC) towards autologous tumours if normal effector cells were used. This type of response was detectable mainly in postoperative sera, and could not be elicited in autologous lymphocytes. On the contrary, autologous sera inhibited CTX of meningioma effector cells. The data suggest that meningiomas can induce a complex immunological response in the host, which is dependent on the presence or absence of a large tumour burden.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1977

Influence of surgery and dexamethasone on cell-mediated immune responses in patients with meningiomas.

Cell-mediated cytotoxicity (CTX) was studied in meningioma patients before and within 2 weeks of complete excision of the tumour, using the [3H]-prolin- microcytotoxicity test. Three of 7 patients tested before surgery showed specific CTX, 2 revealed a "non-specific" (tumour-unrelated) response, and 2 were non-reactive. After surgery, CTX decreased from 84 to 50% in one patient and became negative in 2 others previously positive. One of 2 patients showing "non-specific" CTX preoperatively became positive, while the other remained unchanged. All patients were receiving dexamethasone (DXM) at the time they were tested. Lymphocyte responses to PHA were not significantly different before or after surgery (i.e. after prolonged treatment with DXM), from healthy controls. Blocking activity could be detected in the sera of all 3 patients before surgery. This activity was not specific for meningiomas. Paradoxically, the same sera did not inhibit the proliferative response to PHA. Serum from only one patient consistently suppressed the blastogenic response of homologous lymphocytes to PHA. Inhibitory activity was associated with the IgG fraction of his serum.

Cytotoxicity Tests, Immunologic↗
PubMed1976

Cell-mediated immune response of patients with meningiomas defined in vitro by a [3H]proline microcytotoxicity test.

Cell-mediated cytotoxicity (CTX) of meningioma patients was assessed postoperatively by a [3H]proline microcytotoxicity test. Autologous and allogeneic tumour cells were used for prelabelling with isotope and peripheral blood lymphocytes added in a ratio of 200:1. After 60 hg the plates were washed and residual CMP counted. Control target cells consisted of normal skin fibroblasts. CTX was calculated in percentage reduction compared to cultures incubated with control lymphocytes. Specific CTX on meningioma cells (i.e. not destroying control cells) greater than 20% was considered 'positive' if significant at P less than 0-05. Fifteen of twenty-three meningiomas showed specific CTX (65%). Among eight CNS tumours of different type and thirteen non-malignant diseases and normals only three (14%) were specifically cytotoxic for meningioma cells. A cross-reaction could be demonstrated between autologous and allogeneic meningioma target cells. However, no activity of lymphocytes from patients with meningiomas on glioblastoma cells and foetal brain tissue could be found at the ratio used for evaluation. Evidence is presented indicating that a cellular immune response as measured in the microcytotoxic test may be dependent on a residual or recurrent tumour in the body.

Antigens, Neoplasm↗
PubMed1975

[The lymphocyte cytotoxicity test in tumor immunology (author's transl)].

The cytotoxic action of lymphocytes on cancer cells in vitro indicates sensitization of the patient against his own tumor. The technical difficulities of this test and possibilities of standardization and simplifying the procedure are discussed. Critical steps are isolation of lymphocytes and culturing target cells without loosing their specific antigenic structure. The need for specificity controls both for lymphocytes and tumor cells is emphasized. Labelling tumor cells with isotopes represents a major improvement in evaluating the result. The role of thymus- and bone marrow-dependent lymphocytes as well as blocking factors in the serum of tumor patients can be analyzed in the cytotoxic assay. A better understanding of these mechanisms may facilitate a therapeutic approach by manipulating the interaction of tumor cells and host.

Animals↗