Melphalan-induced enhancement of antitumor immune reactivity in thymocytes of adult BALB/c mice bearing a large MOPC-315 tumor.

At no stage of tumor growth are thymocytes from MOPC-315 tumor bearers capable of bringing about the generation of enhanced antitumor cytotoxicity when added to immunization cultures of syngeneic normal spleen cells and "autochthonous" tumor cells. However, by Day 7 after low-dose melphalan [L-PAM (L-phenylalanine mustard)] therapy of mice bearing a large (greater than or equal to 20 mm) s.c. MOPC-315 tumor, their thymocytes exhibit such activity and it persists for at least 17 additional days. The ability of thymocytes from L-PAM-treated MOPC-315 tumor bearers to bring about the generation of enhanced antitumor cytotoxicity when added to immunization cultures of normal spleen cells and MOPC-315 tumor cells is evident over a 10-fold range of responder/stimulator cell ratios, and requires the presence of the thymocytes within the first day after initiation of the 5-day immunization cultures. In addition, immunization cultures containing normal spleen cells and thymocytes from L-PAM-treated MOPC-315 tumor bearers exhibit enhanced antitumor cytotoxicity by Day 4 after culture initiation that persists for at least 3 additional days. Thymocytes from L-PAM-treated MOPC-315 tumor bearers are able to bring about the generation of enhanced antitumor cytotoxicity only in response to stimulation with autochthonous tumor cells but not in response to stimulation with unrelated allogeneic EL4 tumor cells. The apparent specificity of the enhanced antitumor immune reactivity of thymocytes from L-PAM-treated MOPC-315 tumor bearers is not the result of extensive metastasis of tumor cells to the thymus. In fact, no tumor cells were found in the thymuses of MOPC-315 tumor bearers with methods that can detect 1 X 10(3) tumor cells, indicating that if MOPC-315 tumor cells metastasize at all into the thymus, the thymuses of mice bearing a large MOPC-315 tumor contain fewer than 1 X 10(3) tumor cells. Thus, thymocytes from mice which are engaged in the eradication of a large MOPC-315 tumor display enhanced antitumor immunity in response to stimulation with the autochthonous tumor cells. Such thymocytes may prove important to the outcome of low-dose L-PAM therapy for mice bearing a large MOPC-315 tumor, since the low-dose chemotherapy requires the contribution of T-cell-dependent antitumor immunity for its therapeutic effectiveness.

Importance of tumor-specific cytotoxic CD8+ T-cells in eradication of a large subcutaneous MOPC-315 tumor following low-dose melphalan therapy.

We have previously demonstrated that depletion of CD8+ T-cells by the use of a monoclonal anti-Lyt-2.2 antibody abolishes the curative effectiveness of low-dose melphalan (L-phenylalanine mustard; L-PAM) therapy for BALB/c mice bearing a large (greater than or equal to 20 mm) s.c. MOPC-315 tumor and extensive metastases (Mokyr et al., Cancer Res., 49: 4597-4606, 1989). Here we show that as a consequence of low-dose L-PAM therapy, CD8+ T-cells accumulate in the s.c. tumor nodules of MOPC-315 tumor bearers. Specifically, an 80-fold increase in the number of CD8+ T-cells was seen within 5 days after the chemotherapy. Treatment of MOPC-315 tumor bearers with low-dose L-PAM in conjunction with monoclonal anti-Thy-1.2 or anti-Lyt-2.2 antibody, in contrast to treatment with monoclonal anti-L3T4 antibody, prevented the appearance of the massive CD8+ T-cell infiltrate in the s.c. tumor nodules. Fresh CD8+ T-cells derived from s.c. MOPC-315 tumor nodules that were regressing as a consequence of low-dose L-PAM therapy exhibited a potent direct lytic activity against the MOPC-315 plasmacytoma in a short-term in vitro assay. The specificity of the lytic activity exhibited by the CD8+ T-cells was illustrated not only by the inability of the CD8+ T-cells to lyse two antigenically unrelated thymomas (the WEHI 22.1 and the EL-4) and a natural killer-sensitive lymphoma (the YAC-1), but also by their relatively weak lytic activity against an antigenically related plasmacytoma (the MOPC-104E). Thus, CD8+ T-cells that infiltrate the s.c. tumor nodules of MOPC-315 tumor bearers following low-dose L-PAM therapy most likely exploit a CTL-type lytic mechanism to eradicate at least part of the large tumor burden not eliminated by the direct antitumor effects of the drug.

Importance of Lyt 2+ T-cells in the curative effectiveness of a low dose of melphalan for mice bearing a large MOPC-315 tumor.

We have previously demonstrated that the curative effectiveness of a low dose (2.5 mg/kg) of melphalan (L-phenylalanine mustard; L-PAM) for mice bearing a large s.c. (approximately 20 mm in diameter) MOPC-315 tumor and extensive metastases requires the participation of T-cell-dependent antitumor immunity in tumor eradication (S. Ben-Efraim et al., Cancer Immunol. Immunother., 15: 101-107, 1983). Here we show that the Lyt 2+ T-cells, and not the L3T4+ T-cells, participate in the cure of such tumor-bearing mice by a low dose of L-PAM. Specifically, depletion of Lyt 2+ T-cells from mice bearing a large MOPC-315 tumor by treatment with monoclonal anti-Lyt 2.2 antibody abolished the curative effectiveness of the low dose of drug. In contrast, depletion of L3T4+ T-cells from mice bearing a large MOPC-315 tumor by treatment with monoclonal anti-L3T4 antibody did not reduce significantly the curative effectiveness of the low dose of drug. Histological examination of tumor nodules on various days following low-dose L-PAM therapy revealed widespread lymphocytic infiltration by Day 5 following the chemotherapy, and this infiltration was drastically reduced when the L-PAM-treated tumor bearers were treated with either anti-Thy 1.2 or anti-Lyt 2.2 antibody but not with anti-L3T4 antibody. The antitumor immunity exhibited by Lyt 2+ T-cells derived from mice which were in the process of eradicating a large MOPC-315 tumor following low-dose L-PAM therapy was exploited successfully to confer systemic antitumor immunity to mice bearing a barely palpable tumor. Specifically, the adoptively transferred Lyt 2+ splenic T-cells, in conjunction with a subcurative dose of L-PAM, brought about the cure of most mice. The Lyt 2+ splenic T-cells from L-PAM-treated MOPC-315 tumor bearers were also found to be capable of exerting a direct potent lytic effect against MOPC-315 tumor cells in an antigen-specific manner. Thus, it is conceivable that the direct cytotoxic activity of Lyt 2+ T-cells for MOPC-315 tumor cells is responsible, at least in part, for the ability of the Lyt 2+ T-cells from L-PAM-treated MOPC-315 tumor bearers to bring about the eradication of the tumor burden not eradicated through the direct antitumor effects of the low dose of drug.

Computerizing guidelines to improve care and patient outcomes: the example of heart failure.

Increasing amounts of medical knowledge, clinical data, and patient expectations have created a fertile environment for developing and using clinical practice guidelines. Electronic medical records have provided an opportunity to invoke guidelines during the everyday practice of clinical medicine to improve health care quality and control costs. In this paper, efforts to incorporate complex guidelines [those for heart failure from the Agency for Health Care Policy and Research (AHCPR)] into a network of physicians' interactive microcomputer workstations are reported. The task proved difficult because the guidelines often lack explicit definitions (e.g., for symptom severity and adverse events) that are necessary to navigate the AHCPR algorithm. They also focus more on errors of omission (not doing the right thing) than on errors of commission (doing the wrong thing) and do not account for comorbid conditions, concurrent drug therapy, or the timing of most interventions and follow-up. As they stand, the heart failure guidelines give good general guidance to individual practitioners, but cannot be used to assess quality or care without extensive "translation" into the local environment. Specific recommendations are made so that future guidelines will prove useful to a wide range of prospective users.

Melphalan-induced appearance of potent antitumor immune reactivity in tumor bearer lymphocytes co-expressing the Lyt 2 and the L3T4 antigens.

We have previously shown that Sephadex G-10-adherent spleen cells from mice bearing a large MOPC-315 tumor can suppress the in vitro generation of a primary anti-MOPC-315 cytotoxic response. Here we show that following low dose melphalan (L-phenylalanine mustard; L-PAM) therapy of such tumor bearing mice their Sephadex G-10-adherent spleen cells no longer suppressed but actually brought about the generation of enhanced antitumor cytotoxicity when added to the immunization culture of normal spleen cells and MOPC-315 tumor cells. This immunopotentiating activity of the Sephadex G-10-adherent spleen cells from L-PAM treated MOPC-315 tumor bearers was attributed to T-cells which co-express the Lyt 2 and the L3T4 antigens based on results of experiments employing negative selection. Specifically, depletion of Lyt 2+ cells or of L3T4+ cells abolished the ability of the Sephadex G-10-adherent splenic cell population from L-PAM treated MOPC-315 tumor bearers to bring about the generation of enhanced antitumor cytotoxicity when added to the immunization culture of normal spleen cells. Moreover, the immunopotentiating activity was not restored when a population of Sephadex G-10-adherent spleen cells depleted of Lyt 2+ cells was admixed with a population of Sephadex G-10-adherent spleen cells depleted of L3T4+ cells. In light of the unusual phenotype of the immunopotentiating cells in the spleens of L-PAM treated MOPC-315 tumor bearing mice (i.e. Lyt 2+ L3T4+), and since the vast majority of thymocytes in normal adult BALB/c mice co-express the Lyt 2 and the L3T4 antigens, we evaluated the effect of low dose L-PAM therapy on the antitumor immune reactivity of thymocytes from MOPC-315 tumor bearing mice. A low dose of L-PAM was found to render thymocytes from MOPC-315 tumor bearers, but not from normal mice, capable of bringing about the generation of enhanced lytic activity when added to the immunization culture of normal spleen cells and MOPC-315 tumor cells. At the same time, the thymocytes from L-PAM treated MOPC-315 tumor bearers were unable to develop an antitumor cytotoxic response of their own when immunized in vitro in the absence of normal spleen cells. The possibility that the Lyt 2+ L3T4+ immunopotentiating cells in the spleens of L-PAM treated MOPC-315 tumor bearers represent immature cells that have been induced by the chemotherapy to migrate from the thymus into the spleen is discussed.

Using electronic medical records to predict mortality in primary care patients with heart disease: prognostic power and pathophysiologic implications.

OBJECTIVE: To identify high-risk patients with heart disease by using data stored in an electronic medical record system to predict six-year mortality. DESIGN: Retrospective cohort study. SETTING: Academic primary care general internal medicine practice affiliated with an urban teaching hospital with a state-of-the-art electronic medical record system. PATIENTS: Of 2,434 patients with evidence of ischemic heart disease or heart failure or both who visited an urban primary care practice in 1986, half were used to derive a proportional hazards model, and half were used to validate it. MEASUREMENTS: Mortality from any cause within six years of inception date. Model discrimination was assessed with the C statistic, and goodness-of-fit was measured with a calibration curve and Hosmer-Lemeshow statistic. MAIN RESULTS: Of these patients 82% had evidence of ischemic heart disease, 53% heart failure, and 35% both conditions. Mean survival among the 653 (27%) who died was 2.8 years; mean follow-up among survivors was 5.0 years. Those with both heart conditions had the highest mortality rate (45% at 6 years), followed by isolated heart failure (39%) and ischemic heart disease (18%). Of 300 potential predictive characteristics, 100 passed a univariate screen and were submitted to maltivariable proportional hazards regression. Twelve variables contributed independent predictive information: age, weight, more than one previous hospitalization for heart failure, and nine conditions indicated on diagnostic tests and problem lists. No drug treatment variables were independent predictors. The model C statistic was 0.76 in the derivation sample of patients and 0.74 in a randomly selected validation sample, and it was well calibrated. Patients in the lowest and highest quartiles of risk differed more than five-fold in their average risk. CONCLUSIONS: Routine clinical data stored in patients electronic medical records are capable of predicting mortality among patients with heart disease. This could allow increasingly scarce health care resources to be focused on those at highest mortality risk.

A framework for capturing clinical data sets from computerized sources.

The pressure to improve health care and provide better care at a lower cost has generated the need for efficient capture of clinical data. Many data sets are now being defined to analyze health care. Historically, review and research organizations have simply determined what data they wanted to collect, developed forms, and then gathered the information through chart review without regard to what is already available institutionally in computerized databases. Today, much electronic patient information is available in operational data systems (for example, laboratory systems, pharmacy systems, and surgical scheduling systems) and is accessible by agencies and organizations through standards for messages, codes, and encrypted electronic mail. Such agencies and organizations should define the elements of their data sets in terms of standardized operational data, and data producers should fully adopt these code and message standards. The Health Plan Employer Data and Information Set and the Council of State and Territorial Epidemiologists in collaboration with the Centers for Disease Control and Prevention and the Association of State and Territorial Public Health Laboratory Directors provide examples of how this can be done.