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Biomedical subjects

A B Tilden

Publications and source records attributed to A B Tilden.

44 records · Page 3Linked to original sources
PubMed1984

Prostaglandin E2-mediated suppression of cellular immunity in colon cancer patients.

The immune regulation of phytohemagglutinin (PHA) and concanavalin A (Con A) mitogen responses by prostaglandin (PG)-producing suppressor monocytes was examined in 57 patients with colorectal cancer and 55 normal individuals. The blood lymphocyte responses to either PHA or Con A were significantly depressed in 74% of patients compared to normal controls. The mean PHA response for the patients was significantly lower than that for controls (17,649 versus 25,549 cpm, P = 0.02), while the mean Con A response for the patients was also depressed but not as significantly (13,551 versus 18,623 cpm, P = 0.09). The depression of immune competence was greatest in older patients and those with metastatic disease. The addition of indomethacin (1 microgram/ml) to cell cultures of both patients and normal individuals enhanced the mitogen response, suggesting that PGE-producing suppressor cells were operative in both groups. Among the patient group, however, a differential modulation of the immune response by indomethacin was observed. Thus, the addition of indomethacin restored the PHA response in patients almost to normal levels, while the Con A increase was less pronounced. Even after indomethacin treatment, the Con A proliferative response by lymphocytes was significantly depressed in patients as compared to controls (P = 0.002). To prove that indomethacin was blocking excessive PG production by suppressor monocytes in colon cancer patients, we directly measured PGE2 production by peripheral blood mononuclear cells (PBMCs) using a radioimmunoassay. PBMCs from the patients produced significantly greater amounts of PGE2 compared to controls (10.1 versus 5.1 ng/ml, P = 0.0001). This comparison was still significant after adjustment for age and sex. The increased PGE2 production appeared to be selective, since the levels of two other arachidonic acid metabolites, PGF1 alpha and thromboxane B2, were the same or less than control levels. PG-mediated immune suppression of mitogenesis thus appears to be abnormally increased in colon cancer patients, particularly for the PHA response. This abnormality was partially corrected in vitro by incubation of the PBMCs with indomethacin, a prostaglandin synthetase inhibitor.

Adult↗
PubMed1984

Heterogeneity of natural killer lymphocyte abnormalities in colon cancer patients.

p6e monoclonal antibody HNK-1 reacts exclusively with human granular lymphocytes that comprise 16 +/- 1.4% of blood mononuclear cells. In normal individuals, almost all natural killer (NK) and killer (K) cell function resides in this lymphocyte subset. The level of HNK-1+ granular lymphocytes, their stage of differentiation, and NK cell function were examined in 70 colon cancer patients and the results compared with data for 114 age-matched normal individuals. Median levels of granular lymphocytes were significantly depressed in colon cancer patients compared to controls (9% versus 16.5%, P less than 0.0001). Despite the depressed numbers of circulating HNK-1+ cells, NK cell function in the colon cancer patients was essentially the same as in normals (P = 0.78). The HNK-1+ lymphocyte level correlated exactly with NK cell function in about two thirds of normal individuals but only one third of colon cancer patients (P = 0.025). Three possible mechanisms for this dichotomy were examined. First, lymphoid cell subpopulations purified with a fluorescence-activated cell sorter (FACS) were examined for altered NK cell functional activity. HNK-1+ cells from the colon cancer patients exhibited significantly less NK functional activity compared to normals (796 versus 1046 lytic units, P = 0.04). Interestingly, the HNK-1- fraction (predominantly T lymphocytes) had increased NK cell functional activity in the colon cancer patients compared to normals (373 versus 218 lytic units, P = 0.0001). Purified monocytes did not contribute to NK cell functional activity. Second, the functional maturity of the HNK-1+ lymphocytes was correlated with NK activity. Two subsets of HNK-1+ cells were identified by surface membrane markers and purified with the FACS. The more mature HNK-1+ subset (i.e., HNK+Leu-4-M1+) exhibited almost ten times more NK cell functional activity than did the less mature cell fraction (i.e., HNK+Leu-4+M1-) cells in normal individuals (2230 versus 286 lytic units/10(7) cells). Further analysis demonstrated that the ratio of mature to immature HNK+ cells in normal individuals was 3:1, while it was decreased to a 1:1 ratio in colon cancer patients P = 0.005). Third, the influence of prostaglandin-mediated suppression on NK cell activity was examined. PGE2 did not appear to influence NK cell function, since NK cell function was unchanged in vitro in the presence of a prostaglandin synthesis inhibitor.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1983

Depressed levels of granular lymphocytes with natural killer (NK) cell function in 247 cancer patients.

The HNK-1 (Leu-7) monoclonal antibody was used to enumerate and characterize the level of blood granular lymphocytes in 247 cancer patients. The results were compared to 146 control individuals. A fluorescence-activated cell sorter was used to purify blood HNK-1+ cells from cancer patients. The monoclonal antibody identified a homogeneous population of granular lymphocytes with greater than 95% purity. Conversely, virtually 100% of HNK-1- cells from cancer patients were agranular lymphocytes. These results were the same as previously observed in normal individuals, where the HNK-1+ cell fraction contained all the lymphocytes with spontaneous cytotoxicity in natural killer (NK) and killer (K) cell assays. The level of HNK-1+ cells in cancer patients correlated significantly with the patient's age and sex, with older individuals having higher levels and male patients containing a higher proportion than female patients. The levels in the cancer patients were significantly lower than normal controls (p = 0.04). When the results were subdivided by the histologic type of cancer, additional differences were noted. Compared to age and sex-matched controls, significantly depressed levels of HNK-1+ granular lymphocytes were observed in 49 patients with colon cancer (9.7% vs. 15.8%, p = 0.0001), 18 patients with lung carcinoma (11.7% vs. 27.0%, p = 0.0001), 24 patients with breast carcinoma (12.0% vs. 15.5%, p = 0.04) and 64 patients with head and neck carcinoma (15.9% vs. 19.1%, p = 0.05). However, there were no significant differences overall in the average HNK-1+ cell level of 66 patients with melanoma (13.0% vs. 13.5%, p = 0.75) and nine patients with sarcomas (15.8% vs. 14.3%, p = 0.71). Thus, this important subpopulation of granular lymphocytes with NK and K cell function was significantly depressed in most cancer patients. Accounting for the patient's age and sex and the histologic type of cancer was critical to interpreting the results.

Adult↗
PubMed1983

Suppressor cell function of human granular lymphocytes identified by the HNK-1 (Leu 7) monoclonal antibody.

The HNK-1 (Leu 7) differentiation antigen defines a subpopulation of human granular lymphocytes with natural killer (NK) and K cell function. In this study, we investigated whether HNK-1+ cells, identified with the monoclonal antibody and purified with a fluorescence-activated cell sorter (FACS), could function as suppressor cells. The results demonstrated that purified HNK-1+ cells efficiently suppressed both PWM-induced IgG production by B cells and T cell proliferation in mixed lymphocyte reactions (MLR). Manifestation of this suppressor cell activity required immune complex activation and was partially sensitive to 2000 rad irradiation. This suppressor cell activity was predominantly mediated by a subset of HNK-1+ cells that have previously been shown to have maximum NK function and lack expression of the E rosette (ER) receptor and T cell antigens (e.g., T3 and T8). Thus, HNK-1+ER- cells suppressed a MLR by an average 52%; HNK-1+ER+ were one-half as efficient, causing an average 23% suppression. For comparison, we also examined the characteristics of Leu 2a+ suppressor T lymphocytes. In contrast to HNK-1+ cells, unactivated Leu 2a+ cells suppressed both B and T cell responses. This suppressor activity was not augmented by immune complex activation and was absolutely radio-sensitive in PWM assays. HNK-1+ cells, especially the HNK+ER- subset, can therefore mediate suppressor cell function in addition to their spontaneous cytotoxic function. Furthermore, some of their suppressor cell properties are distinct from those attributed to other types of suppressor lymphocytes.

Antibodies, Monoclonal↗
PubMed1982

Excessive prostaglandin E2 production by suppressor monocytes in head and neck cancer patients.

The proliferative response of peripheral blood mononuclear cells (PBMC) to the mitogens PHA and Con A significantly depressed in 86% of 45 head and neck cancer patients compared with 44 normal controls. This depression of immune competence was greatest in older patients and in those with more advanced disease stages. The abnormal mitogen responses could be restored toward normal (especially with Con A stimulation) by incubating the cells with either of two prostaglandin synthetase inhibitors (indomethacin or RO-205720). This augmentation of immune response was independent of other factors, including the primary tumor site, disease stage, treatment (surgery, radiation therapy, or chemotherapy) or the patients's age or race. The most likely explanation for this depressed level of immunocompetence was an excessive production of PGE2 by suppressor cells. This was confirmed by the finding that PBMC from patients produced more PGE2 than PBMC from normal individuals (8.4 ng/ml vs. 5.2 ng/ml, p=0.002). This difference was greatest among patients less than 60 years of age whose cultured PBMC produced 91% more PGE2 than controls (p less than 0.0007). Virtually all of the PGE2 was produced by a population of monocytes defined by a monoclonal antibody and purified with a fluorescence-activated cell sorter. Patients with epidermoid cancer of the head and neck thus have an abnormality of immunoregulatory monocytes that can contribute significantly to their depression of cellular immunity by elaborating prostaglandin E2. This abnormality could be partially corrected in vitro by incubating their PMBC with a prostaglandin synthetase inhibitor.

Adult↗
PubMed1982

Immune modulatory effects of indomethacin in melanoma patients are not related to prostaglandin E2-mediated suppression.

Indomethacin significantly enhances the depressed levels of lymphocyte proliferation to the mitogens phytohemagglutinin and concanavalin A in melanoma patients. We postulated that these results were related to an abnormality in prostaglandin E2 (PGE2)-mediated suppression, since this mechanism has previously has previously been demonstrated in patients with Hodgkin's lymphoma and with head and neck carcinoma. However, the results of three experimental approaches did not support this hypothesis. First, in vitro PGE2 production by cultured blood mononuclear cells was the same in 16 melanoma patients as in 45 normal controls (4.9 versus 4.7 ng/ml). Second, lymphocyte sensitivity to PGE2 for melanoma patients was essentially the same as that for normal controls, since exogenous doses of PGE2 inhibited the mitogen responses to the same degree. Third, another prostaglandin synthetase inhibitor (RO-205720), which is structurally unrelated to indomethacin, did not augment the mitogen response in these patients. Thus PGE2 cannot be implicated as a mediator of immunosuppression in melanoma patients. To further examine the immunomodulatory mechanism of indomethacin, we preincubated the drug with purified populations of either lymphocytes or monocytes, which were then recombined and tested for mitogen response. The results suggested that indomethacin had a direct effect on the responding T lymphocytes rather than an indirect effect on monocytes. These are the first studies demonstrating that indomethacin can act directly as a modulator of cellular immune function, independent of PGE2-mediated suppression.

Adult↗
PubMed1981

Indomethacin enhancement of immunocompetence in melanoma patients.

Lymphocyte responses to the mitogens concanavalin A (Con A) and phytohemagglutinin (PHA) are important in vitro parameters of immunocompetence in cancer patients. The tempo and intensity of this response is regulated by monocytes. We found that the blood lymphocyte response to one or both of these mitogens was significantly depressed in 32 of 33 melanoma patients compared to 29 normal control subjects. However, these responses were significantly enhanced when the drug indomethacin, a prostaglandin synthetase inhibitor, was added to cultures of peripheral blood mononuclear cells (PBMCs) from the melanoma patients, but not from the normal control subjects. For example, at a 1 microgram/ml dose of Con A, the mean response of melanoma patients increased from 56% to 81% of the normal mean response, whereas at 20 micrograms/ml PHA the mitogen response increased from 57% to 77% of normal when PMBC were incubated with indomethacin (P less than 0.001). Overall, indomethacin enhanced the mitogen responses of melanoma patients by 35% to 85%, whereas indomethacin increased the response in normal subjects by only 5% to 15%. The mitogen response of monocyte-depleted ER+ lymphocytes for melanoma patients was equivalent to that of normal control subjects, and there was no enhancement of this response in the presence of indomethacin. This suggests that the abnormality was due to an altered function of immunoregulatory monocytes. The enhancement by indomethacin in melanoma patients was not significantly influenced by their stage of disease, age, or the proportion of blood monocytes. The decreased levels of cellular immunocompetence in these melanoma patients, as measured by their lymphocyte proliferative responses to mitogens, therefore appears to be associated with an abnormality in monocyte function that is partially corrected by indomethacin.

Adult↗