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The present study examines the role of monocytes in the in-vitro activation of human T cells and B cells by pokeweed mitogen (PWM). The T cell-dependent PWM-induced B-cell activation process was found to be monocyte dependent. Fluorescence-activated cell sorter (FACS) analysis revealed that upon addition to peripheral blood mononuclear cells, fluoresceinated PWM, at concentrations that provided optimal B-cell and T-cell activation, bound predominantly to human monocytes. The binding of PWM to monocytes was reversible and could be displaced within the first few hours of binding by oligomers of N-acetylglucosamine (GlcNAc). As a functional correlate of the binding studies, it was shown that PWM-pulsed monocytes could induce B lymphocytes to become plaque-forming cells (PFC) and T lymphocytes to undergo proliferation. In contrast, markedly reduced PFC and blastogenic responses were observed when monocyte-depleted B lymphocytes and T lymphocytes were respectively pulsed with PWM and washed, followed by the addition of non-PWM-pulsed monocytes to the cultures. Thus, the initial event in the PWM-induced activation of human lymphocytes, for both in-vitro T-lymphocyte blastogenic responses and B-lymphocyte Ig secretion, appears to be binding of the mitogen to sugar residues on the surface membrane of the monocyte, followed by subsequent interaction with the appropriate lymphocytes. The process of PWM binding to monocytes did not appear to affect the baseline production of interleukin-1 (IL-1) by human monocytes, nor could soluble factors from PWM-pulsed monocytes substitute for intact cells in the initiation of the lymphocyte-activation process. [ABSTRACT FROM AUTHOR]

The differential effects of in vitro cyclophosphamide (CY) on subpopulations of normal human peripheral blood lymphocytes involved in the pokeweed mitogen-induced plaque-forming cell (PFC) response against sheep red blood cells were examined. It was found that the plaque-forming B cells in this system are sensitive to CY over a wide concentration range including concentrations which have a minimal effect on overall cell viability. Kinetic experiments revealed that CY exerts its inhibitory effect on the PFC response only if added very early in culture. Thus, it appears that in vitro CY must exert its inhibitory influence on an early phase of polyclonal B-cell activation. When T-cell enriched (TCE) populations were incubated overnight with high concentration CY and then added back in co-culture to fresh autologous B cells, significant enhancement of PFC responses was observed suggesting a selective inhibition or elimination of a regulatory suppressor cell population found in ICE lymphocyte preparations. Helper T cells are relatively resistant to the inhibitory actions of CY. Thus, human B cells appear to be most sensitive to CY, followed in sensitivity by the suppressor cell populations in the 1-cell fraction with relative resistance of the helper T cells. These observations have direct relevance in understanding the mechanisms of selective action of CY on normal human lymphocyte subpopulations with possible application to disease states in man. [ABSTRACT FROM AUTHOR]

The potential roles of Ca2+ ions in the response of T lymphocytes to stimulation with monoclonal antisera to the T3 antigen were investigated by means of pharmacological agents that predominantly inhibit the flux of Ca2+ ions into cells (verapamil, nifedipine) or the activity of Ca2+-dependent kinases (trifluoperazine, polymyxin B). As assessed by uptake of [3H]thymidine, proliferation induced with anti-T3±recombinant IL-2 at 72 h was inhibited by >80% in the presence of nifedipine at 50 μM, and almost completely arrested (>95% inhibi- tion) with the other agents at the same concentration. Further quantitative assays of the effects of polymyxin B and trifluoperazine on C-kinase labelling of exogenous substrate showed a major reduction with both agents, but inhibition was substantially greater with polymyxin B that with trifluoperazine (IC50=14 and 70 μM respectively). These results were confirmed by qualitative assessment of Ca2+/phospholipid-dependent phosphorylation of endogenous substrates, which demonstrated major phosphoproteins of MW 56,000, 52,000, 43,000, and 20,000, and dose-dependent reduction in labelling in the presence of polymyxin B. Similar results were obtained under more physiological conditions in intact cells labelled with 32P orthophosphate. These findings indicate several possible roles for Ca2+ in T-cell activation, and several possible levels of activity, including modulation of caimodulin-dependent kinases and effects on Ca2+/phospholipid-dependent kinases and Ca2+ channels. [ABSTRACT FROM AUTHOR]

The effector cells for spontaneous cytotoxicity against anchorage-dependent human or mouse tumour cell lines in 72-h iododeoxyuridine-release-assay by normal human peripheral blood cells (PBMNC) or monocyte-enriched fractions were analysed by the use of monoclonal antibodies. PBMNC or adherent or elutriated monocyte-enriched populations of PBMNC were depleted of monoclonal antibody-reactive cells by complement-dependent lysis or separated into monoclonal-antibody-positive or -negative subsets by an indirect resetting technique followed by Ficoll-Hypaque density gradient separation. The experimental data indicated that in both PBMNC and monocyte-enriched populations, and appreciable proporation of the effector cells with cytolytic activity against adherent human or mouse tumour target cells were positive with B73,1.1 (an antibody with a high degree of selectivity for natural killer (NK) cells), B43,4.1 (or OKM1), and with OKT11a (an antibody recognizing the receptors for sheep erythrocytes), and had the morphology of large granular cells, which have previously been shown to mediate NK activity. These effector cells were mostly negative for BRL,1, BRL,2, B52.1.1, B44.1.1, B13.4.1 and DR antigens, unlike classical monocytes. Some cells which are cytotoxic for the adherent mouse, SV-40-transformed kidney tumour line, TU-5, may bear B52.1.1 or other monocyte-like antigens. Taken together, these results indicate that, in monocyte-enriched populations, both NK cells and monocytes have cytotoxic effector activity against various human and mouse adherent target cell lines. [ABSTRACT FROM AUTHOR]

Human peripheral blood mononuclear cells (PBMNC) wore found lo be cytotoxic for mouse or human anchorage-dependent target cell lines in a 48-72 h [125I]iododeoxyuritline (IUOR) release assay. Unfractionated, adherent or nonadherent cells had significant levels of cytoioxicity, as did cells fractionated according to size into 'lymphocytes' or 'monocytes' by elutriation. Intermediate size cells, not enriched for monocytes, had high levels of cytotoxicity. In all fractions tested, including adherent populations, some cells with the morphology of large granular cells were observed. Treatment of all fractions with interferon (IFLrA, a purified, recombinant α-IFN) boosted cytotoxicity against four target cells lines. Treatment with lymphokines containing putative 'macrophage-activating factor' (MAF) also enhanced cytotoxicity in fractions depleted of monocytes. Culture in fetal bovine serum enhanced cytotoxicity mainly in unfractionated and nonodherent PBMNC. These experiments indicated that N K-like cells can be appreciable contaminants in elutriator-purified monocyte-enriched or adherent cell populations and thereby contribute to observed cytotoxicity, particularly after pretreatment with IFN or other stimulatory factors. [ABSTRACT FROM AUTHOR]

Normal human monocytes were negatively selected from leucapheresis cell suspensions by countercurrent ccntrifugation-elutriation in high yield with a mean purity of 93.5%. The combination of the novel methods of negative cell selection and suspension cell culture has provided the opportunity to study serially over several days the morphologic and functional changes of monocytes from a single donor as they matured in culture to typical macrophages. Human monocytcs nearly double in size during the first week of culture, experiencing near daily increases in cell volume. This was associated with changes in the ultrastructure of these cells, including the development of numerous small knob-like projections on the cell membrane and the proliferation of microtubules and filamentous structures within the cell cytoplasm during the first 6 days of culture. Peroxidase activity declined during the first 4 days of culture, whereas 5′-nucleotidase activity was acquired during the first 48 h of culture. Lysozyme activity in the cultures increased from day 2 to day 6 of culture. The phagocytic capacity of monocytes for IgG-coated erythrocytes increased dramatically during the first week of culture, but the cytotoxic capability of monocytes against similar targets in an antibody-dependent cytotoxicity assay declined to nearly half of base-line levels by day 2 of culture and remained at this diminished level during subsequent days in culture. [ABSTRACT FROM AUTHOR]

The risk factor, stress engagement, and coping experiences of African American youth are not well understood. Given the stressors of racism, hopeless perceptions of urban youth, and violence experience and exposure, anger experience and expression are reasonable resilient and risky reactions to this atmosphere of hostility. This study analyzed the impact upon the anger management of adolescents when calamity fears, neighborhood social capital, and kinship social support are known. The findings suggest that when the calamity fears of youth are high, their anger experience and expression is minimized. This finding was prominent for adolescents living in high-risk neighborhoods. Kinship social support showed a positive relationship to anger suppression for youth in high-risk environments. Implications for understanding the phenomenological stress and coping experiences of African American youth are discussed.

Video education is the most popular and effective medium for informing the adolescent population. This study investigated the impact of a culturally relevant HIV/AIDS video education. One hundred and ninety-four African-American teenagers were assigned to either a culturally sensitive or culturally dissimilar video education intervention. Results indicate that both interventions were effective in increasing AIDS knowledge scores. An interaction effect was found between levels of perceived AIDS risk knowledge and participation in the culturally sensitive intervention (CSV). Only the CSV intervention was effective with adolescents who claimed to "know a lot" about AIDS (e.g., "Know-It-All" subgroup). Students in both conditions who were worried about getting AIDS demonstrated higher AIDS risk knowledge at post-assessment. This study provides further evidence of within-ethnicity diversity among African-American youth and for developing culture- and subgroup-specific HIV/AIDS education.

Community based AIDS prevention programming and research in minority neighborhoods are growing. The AIDS epidemic has demoralized many minority communities and has added to enormously stressing social conditions. Obstacles to effective AIDS prevention programming must be removed before stable, accessible, and culturally relevant services can be provided. A pilot study was conducted to identify the obstacles to AIDS research or intervention in ethnic minority neighborhoods. Twenty-nine administrators and counselors from Community Based Organizations completed questionnaires concerning reasons for entering the field of AIDS prevention, enjoyment of work, hopefulness towards AIDS efforts, priority of AIDS funding, and opinions about most and least helpful prevention efforts in minority communities. Barriers identified as most problematic include insufficient funds, lack of culturally relevant materials, denial of the epidemic in minority communities, distrust of majority culture institutions, and myths/beliefs regarding AIDS contraction, transmission, and origin. Future research ideas are identified to improve culturally relevant AIDS prevention interventions in ethnocultural neighborhoods.

AIDS video education is a major mode of providing information about the spread and prevention of the human immunodeficiency virus (HIV). Very little has been written about the need for culturally salient messages in increasing the acquisition and retention of HIV/AIDS prevention information, even though there is considerable agreement that limited culturally sensitive information is reaching African-American youth. This investigation sought to ascertain the impact of a culturally similar AIDS video on the acquisition of AIDS knowledge and endorsement of HIV/AIDS prevention beliefs. This study randomly assigned classes of African-American teenagers to one of two treatment groups: culturally similar video (CSV) AIDS education and culturally dissimilar video (CDV) AIDS education. Results suggest that the CSV group demonstrated significant improvement in pre- to post- AIDS knowledge scores compared to the CDV group (using ANCOVA procedures). The intervention was not significant in demonstrating change in beliefs about prevention. Implications for the development of HIV/AIDS prevention programs for inner-city African-American youth are discussed.

Interest in retinoids as therapeutic agents has developed as a result of the observations of remission induction with all-trans retinoic acid (tRA) in patients with acute promyelocytic leukemia (APL), and of high objective response rates noted with the combination of cis-retinoic acid (cRA) with interferon-alpha in squamous cell carcinomas of skin and cervix. The therapeutic experience with RA in APL is discussed in this article from the perspectives of new information concerning retinoid biology, observations related to the development of the retinoid syndrome, complex pharmacology of this agent, and possible explanations for development of retinoid resistance. The current National Cancer Institute-supported drug development strategy for RA used alone or in combination with other differentiating agents, and the potential therapeutic uses in cancer for other retinoids are also discussed.

This study reports effects of halothane on tumor cells in vitro. Cells from the human colon cancer cell line HT-29 were exposed to various concentrations of halothane for 8-72 h. The effect of this exposure on this colon cancer cell line, with and without coincubation with the biologic response modifier gamma-interferon (IFN-gamma), was studied. Using the tumor target cell survival (TTCS) assay, concentrations of halothane from 0.5 to 2% markedly augmented the antitumor activities of IFN-gamma against HT-29. The tumor cell cytostatic effects of IFN-gamma in the 0.75-6-unit/ml range were increased nearly 400% by concentrations of halothane as low as 1%. These results were confirmed in a separate cytolytic assay (Indium-111 release assay), which revealed that halothane concentrations in the 2-4% range markedly increased the cytolytic capacity of IFN-gamma at doses of IFN-gamma between 75 and 1,250 units/ml. The cytolytic activity of IFN-gamma was increased nearly 300% by doses of halothane as low as 1%. A nearly identical pattern of augmentation of IFN-gamma-induced antitumor activity was observed when the known calmodulin inhibitor trifluoperazine (TFP) was coincubated with IFN-gamma. At concentrations of 4-10 microM, the antitumor activity of IFN-gamma was increased nearly 400%. These observations suggest that the pattern of halothane potentiation of the antitumor activity of IFN-gamma is similar to that exhibited by known calmodulin inhibitors.

Several groups have described the efficacy of interleukin 2 (IL-2) plus lymphokine-activated killer (LAK) cells in the treatment of cancer patients with significant response rates noted in patients with renal cell cancer and malignant melanoma; however, the optimum regimen remains undefined. The Biological Response Modifiers Program of the National Cancer Institute conducted two consecutive Phase I/II studies evaluating the toxicity and clinical efficacy of different methods of IL-2 and LAK cell therapy. In the first trial, we modified the standard Rosenberg regimen by decreasing the duration of priming in an attempt to reduce the toxicity related to this phase of the therapy and thereby administer more IL-2 doses with the LAK cells. In the second trial, we used a continuous i.v. infusion IL-2 regimen and altered both the leukapheresis procedure and the LAK cell culture techniques based on our in vitro and preclinical studies suggesting that 2-day LAK cells were superior. Thirty cancer patients received i.v. bolus IL-2 at 100,000 units/kg every 8 h for 3 days during priming and for 5 days during LAK cell administration. A second group of 22 cancer patients received IL-2 by continuous i.v. infusion at 3 x 10(6) units/m2 for 5 days during priming and an additional 5 days of IL-2 with the LAK cell phase of the treatment. The timing of the start of the leukapheresis procedures, their duration and number, and the LAK cell culture techniques differed in the two trials. Overall, 52 patients with various cancers were treated. The toxicities associated with each regimen were similar to those seen in other IL-2 plus LAK cell trials. Four patients (one each with melanoma and diffuse large cell lymphoma and two with renal cell cancer) exhibited partial responses lasting 2, 4, 10, and 15+ mo. Serial tumor biopsies from treated patients demonstrated that therapy can produce a marked mononuclear cell infiltrate and an increase in HLA-DR expression on tumor cells. There was no difference in the overall response rate between the two regimens, but toxicity was less with continuous i.v. infusion IL-2. The 5-day continuous i.v. infusion regimen resulted in significantly higher rebound lymphocytosis, cell yield from leukapheresis, and number of LAK cells harvested from culture.