A survey of drug-resistant Mycobacterium tuberculosis and its relationship to HIV infection.

OBJECTIVE: To compare the prevalence of drug-resistant tuberculosis disease among patients with and without HIV infection. DESIGN: An historical prospective evaluation of patients with culture-proven tuberculosis reported between January 1988 and December 1995. SETTING: A major metropolitan county public health department. PATIENTS: A total of 802 consecutive culture-positive tuberculosis patients were eligible for inclusion in the study. HIV serologic testing and drug susceptibilities were completed on 741 (92%) eligible patients. Of these patients, 646 tested HIV-negative and 95 (12.8%) tested HIV-positive. Patients not tested for HIV (n = 59) and without drug susceptibilities (n = 2) were excluded from the analyses. Outpatient management was based on a policy of universal directly observed therapy. MAIN OUTCOME MEASURES: Patient HIV status, initial drug resistance and acquired drug resistance. Isolates were characterized for resistance to isoniazid, rifampin, rifabutin, ethambutol, streptomycin, capreomycin, kanamycin and ethionamide. Determination of initial resistance was based on the first available susceptibility study and acquired resistance on subsequent susceptibility studies. RESULTS: Initial drug resistance was found in 55 (8.5%) HIV-negative patients and four (4.2%) HIV-positive patients. Acquired drug resistance occurred in five (0.8%) HIV-negative patients and one (1.1%) HIV-positive patient. These differences were not statistically significant. CONCLUSIONS: HIV infection is not a risk factor for drug-resistant tuberculosis. Increased drug resistance in HIV infected tuberculosis patients reflects a failure of tuberculosis control in the underlying population.

Peripheral blood mononuclear-cell interleukin-2 production, receptor generation and lymphokine-activated cytotoxicity in inflammatory bowel disease.

The interleukin-2 pathway is essential for the normal immune response to antigen stimulation; we have examined the possibility that this may underlie abnormal peripheral blood lymphocyte immunoregulatory function that has been observed in patients with inflammatory bowel disease. We studied 11 patients with Crohn's disease and 5 with ulcerative colitis, all with quiescent disease activity. Peripheral blood mononuclear cells were isolated from these patients and from healthy age- and sex-matched controls. Interleukin-2 production after mitogen and phorbol-myristate acetate stimulation was similar in both groups: 381 +/- 71 (mean +/- SE) U/ml by control cells and 451 +/- 70 by patient cells. Interleukin-2 receptor generation was also measured pre- and poststimulation by labeling with anti-Tac antibody. This was 10.45 +/- 1 and 69.95 +/- 3.85% for control cells and 11.41 +/- 1.38 and 60.9 +/- 4.25% for patients cells. Finally, we examined the response of these cells to interleukin-2 stimulation by generating cells with direct cytotoxicity to 51Cr-labeled Daudi-cell targets. Control cells caused 59.5 +/- 46% 51Cr release, whereas patient cells caused 50.8 +/- 5.18% release. None of the above results achieved statistical significance. We conclude that the peripheral blood interleukin-2 pathway is normal in inactive inflammatory bowel disease.

Suppression of antibody responses to topically applied antigens by ultraviolet light irradiation. Induction of phototolerance.

C3Hf/HeN or BALB/c mice, exposed to acute ultraviolet (UV) irradiation and skin-sensitized through the irradiated skin site with soluble protein antigens, exhibit humoral tolerance to subsequent systemic challenge with antigen. We have termed this phenomenon "phototolerance" (PT). With the doses of UV radiation used, PT induction is restricted to the irradiated skin site and is observed only if sensitization is performed via the cutaneous route. PT is antigen specific and operates at the afferent level of the immune response. While single PT induction regimens result in transient humoral suppression, multiple inductions before each systemic challenge can maintain the response at low levels. The capacity to induce PT to a variety of soluble protein antigens may have potentially important clinical applications.

Lymphokines in autoimmunity: relationship between interleukin-2 and interferon-gamma production in systemic lupus erythematosus.

Interleukin-2 (IL-2) and interferon (IFN) are potent immunoregulatory factors. Recently, it has been demonstrated that IL-2 production is necessary for IFN-gamma synthesis. Thus, defects in IL-2 production could lead to defects in IFN-gamma production. Indeed, in systemic lupus erythematosus, defects in IFN-gamma and IL-2 production have been noted. To test this hypothesis, IL-2 and IFN-gamma production rates by peripheral blood mononuclear cells PBMC were measured simultaneously after stimulation by concanavalin A (Con A) and phorbol myristic acetate (PMA). IL-2 activity was determined employing HT-2, a cell line with an absolute growth requirement for IL-2. IFN-gamma activity was assessed using a standard viral plaque inhibition assay. IL-2 production in normal controls (n = 6) was 14.7 +/- 9.4 units/ml and in SLE patients (n = 10), 18.0 +/- 10.5 units/ml (P greater than 0.05). IFN-gamma production in controls was 74.7 +/- 43.7 units/ml and in SLE patients, 68.8 +/- 35.4 units/ml (P greater than 0.05). Only one SLE patient, who had moderately active disease, demonstrated defects in IL-2 synthesis (less than 4 units/ml) and IFN-gamma production (16 units/ml). Thus, production of these lymphokines in SLE patients was largely normal in response to Con A-PMA. These results imply that the intrinsic pathways of IFN and IL-2 production are basically normal in most SLE patients although defects in production of these lymphokines can occur. The defects in IL-2 and IFN production in SLE previously reported may be secondary to an impaired cellular response to the selected inducing agent rather than a primary defect in the actual ability to produce these important lymphokines.

Cross-reactive transplantation antigens between UV-irradiated skin and UV-induced tumors.

The fate of ultraviolet (UV) light-induced tumors transplanted into syngeneic hosts bearing skin grafts from UV-irradiated donors was studied. Our results suggest that UV-irradiated skin and UV-induced tumors express common antigens. Further, these results may bear on the question of how subcarcinogenic doses of UV radiation can effect the generation of tumor antigen-specific T suppressor cells prior to the existence of UV-induced tumors. Specifically, normal C3Hf/HeJ mice were grafted with UV-irradiated, or normal skin and subsequently implanted with either regressor, progressor, or conversion type UV-induced tumors. Animals bearing UV skin grafts were: a) effectively immunized against conversion type tumors, b) exhibited no differences against regressor type tumors, and c) allowed progressor type tumors to grow at an accelerated rate.

Impaired natural killer cell function in systemic lupus erythematosus. Relationship to interleukin-2 production.

Immune regulation requires clonal expansion of regulatory T cells which is dependent on the presence of interleukin-2 (IL-2). Previously, both natural killer (NK) cell function and IL-2 production were found to be depressed in systemic lupus erythematosus (SLE). This study was designed to determine the relationship between IL-2 production and NK cell activity in SLE. NK activity as determined by a standard 4-hour 51Cr-release assay was impaired in SLE (11.0 +/- 5.1 lytic units/10(7) cells) compared with controls (25.1 +/- 7.1 lytic units/10(7) cells) (P less than 0.05). IL-2 production was induced with concanavalin A and phorbol ester and quantitated using the IL-2 dependent cell line HT-2. IL-2 production was impaired in only 1 SLE patient, despite concomitant abnormalities in NK function in the SLE group as a whole. Moreover, in patients with impaired NK activity, incubation of lymphocytes with exogenous IL-2 did not restore NK activity to normal levels. These findings demonstrate that impaired NK activity in SLE is independent of IL-2 production and that defects in IL-2 production in SLE may not be as common as previously reported.

Establishment of a continuous T cell line capable of suppressing anti-tumor immune responses in vivo.

This report describes the induction, phenotypic characteristics, and functional properties of a continuous suppressor T cell line. This cell line, UV1, is capable of suppressing anti-tumor immune responses both in vivo and in vitro. The UV1 cell line was derived from a T cell-enriched (nylon wool nonadherent, Ia-negative panned fraction) spleen cell population from a ultraviolet radiation-(UV) exposed BALB/c Wehi mouse. By using an in vivo functional assay designed to demonstrate tumor-specific UV-induced suppressor T lymphocyte (Ts cell) activity, it was found that UV1 cells were capable of rendering normal syngeneic mice susceptible to the growth of UV-induced regressor tumors. In addition to their suppressive activity in vivo, UV1 cells displayed in vitro suppressive activity by blocking the differentiation of cytotoxic T cells from the draining lymph nodes of UV-tumor immunized animals. By flow cytometric analysis it was determined that UV1 cells expressed a number of T lymphocyte differentiation antigens and did not express any detectable amounts of surface immunoglobulin, I-A or E/C antigens, Fc receptors, or macrophage antigens. These data suggest that the UV1 cell line may be representative of the UV-induced Ts cell population and provide a potential means for studying UV-induced immunoregulatory mechanisms in greater detail.

Ultraviolet light-induced suppression of antigen presentation.

Ultraviolet (UV) light irradiation of animals results in the development of specific T suppressor cells that inhibit antitumor immune responses. It is thought that suppression may arise as a consequence of altered antigen presentation by UV-irradiated epidermal cells. This hypothesis is based on evidence demonstrating that specific lymphoid tissues from UV-irradiated hosts exhibit impaired antigen-presenting function and that animals cannot be contact sensitized when antigens are applied to a UV-irradiated skin site. Langerhans cells of the skin are likely candidates as targets of UV-induced defects in antigen presentation as they bear Fc and C3b receptors, express Ia antigens, are of bone marrow origin, and are capable of presenting antigen in vitro. We speculate on the possible clinical usefulness of UV-induced tolerance to specific antigens such as those encountered in monoclonal antibody therapy and tissue transplantation.

Modification of immunological potential by ultraviolet radiation. II. Generation of suppressor cells in short-term UV-irradiated mice.

When normal mice are exposed for short periods to ultraviolet light (UV), they support the progressive growth of transplanted syngeneic UV-induced tumors. Normal nonirradiated mice almost always reject these tumor implants. The UV-mediated suppression of the antitumor response can be adoptively transferred to normal syngeneic mice with lymphoid cells derived from short-term UV-irradiated donors. Transfer of the suppressive effect is dosage dependent and also appears to require the presence of viable T lymphocytes. Suppressive activity was observed in both the spleen and thymus of UV-irradiated donors. In the preceding paper we have established that UV irradiation does not cause a general depression of testable immune functions. Collectively these data suggest that short-term UV irradiation of mice leads to an increase in suppressor cell activity, thereby causing an inhibition in the host's ability to respond to an antigenic UV-induced tumor. The possible role of this phenomenon in the mechanism of UV carcinogenesis is discussed.

Modification of immunological potential by ultraviolet radiation. I. Immune status of short-term UV-irradiated mice.

C3Hf/HeN mice support the progressive growth of most transplanted syngeneic ultraviolet (UV) light-induced tumors following short-term UV exposure whereas nonexposed mice reject these tumors. Because an immunosuppressive role in UV-mediated tumor susceptibility might be suggested by these observations, a comparison of several immunological parameters has been conducted. These include antibody production, proliferation in response to antigenic and mitogenic stimulation, and the generation of cytotoxic effector cells by normal or short-term UV-exposed mice. The results indicate that short-term UV irradiation of mice does not result in any readily detectable alterations of the host's immune system other than the consistent loss of the antitumor response mediating rejection of the transplanted UV-induced tumor.