CD8+ T lymphocyte control of HIV replication in cultured CD4+ cells varies among infected individuals.

Production of the human immunodeficiency virus (HIV) by cultured peripheral blood mononuclear cells (PMC) from many seropositive individuals is inhibited by the presence of CD8+ T lymphocytes. In a study of 10 subjects, high levels of virus replication could be detected in cultures of purified CD4+ cells, but not in unseparated PMC. Addition of highly purified, autologous CD8+ cells to the enriched CD4+ cells resulted in a dose-dependent inhibition of HIV growth and revealed that for some individuals, even low numbers of CD8+ cells can prevent replication of the virus. The data also indicated that culturing enriched CD4+ cells could greatly enhance detection of infectious virus in blood specimens and demonstrated that the CD4+ molecule is expressed on infected T cells isolated directly from the peripheral blood.

Cyclophosphamide 'pulses' in chronic progressive multiple sclerosis. A preliminary clinical trial.

To our knowledge, this is the first clinical trial in multiple sclerosis (MS) demonstrating the feasibility of directing immunomodulating therapy by monitoring immunologic results. Cyclophosphamide was administered at monthly intervals, escalating the dose until there was a significant reduction in both the number of blood B lymphocytes and helper/inducer (CD4) T cells of 14 patients with chronic progressive MS. The frequency and severity of adverse effects led us to conclude that the regimen is too toxic for the long-term treatment of patients with MS.

An AIDS-related cytotoxic autoantibody reacts with a specific antigen on stimulated CD4+ T cells.

Patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related conditions are known to have abnormalities of T cell subpopulations, including a decreased helper/inducer (bearing the CD4 antigen) to suppressor/cytotoxic (bearing the CD8 antigen) T cell ratio and decreased absolute numbers of T cells with the CD4+ phenotype. Infection of T cells with a retrovirus, termed human immunodeficiency virus (HIV), is thought to be important in these abnormalities. HIV infection alone does not adequately explain the CD4+ T-cell abnormalities seen in AIDS, however, and the nature of T-cell destruction in this disease remains poorly characterized. Here we describe an AIDS-related serum autoantibody that reacts with an antigen of relative molecular mass 18,000 (Mr 18K) restricted to lectin-stimulated or HIV-infected CD4+ T cells. The antibody also suppresses proliferation of CD4+ T cells in vitro and induces cytotoxicity of these cells in the presence of complement. Its role in the development of AIDS merits attention.

Correlation of clinical and immunologic states in multiple sclerosis.

Cyclophosphamide was administered to 14 patients with chronic progressive multiple sclerosis on an intermittent escalating dosage schedule adjusted to maintain numbers of peripheral blood B lymphocytes and helper/inducer (CD4) T cells below the fifth percentile of the normal population. Peripheral blood B cells, T cells, suppressor/cytotoxic (CD8) T cells, CD4 cells, and FcR+-bearing cell numbers and percentages were monitored at one-week to two-week intervals. Clinical status was assessed by neurologic examinations at approximately four-week intervals. Regression analysis revealed a statistically significant correlation between changes in immunologic status and changes in clinical state. The immunologic changes preceded the neurologic changes. Increases in percent of CD8 cells and decreases in percent of CD4 cells forecast improved clinical course. These findings, coupled with other studies, strongly suggest a pathogenetic role for helper and suppressor T cells in the production of clinical signs of multiple sclerosis.

Increased spontaneous immunoglobulin secretion associated with cyclophosphamide-induced immune suppression.

Spontaneous immunoglobulin (Ig) secretion by cells from multiple sclerosis (MS) patients (in the progressive phase) treated with monthly pulse doses of cyclophosphamide (CY) (1000-1600 mg/M2) was measured using the protein A plaque assay, to evaluate the effect of CY treatment on B-cell function. Surprisingly, an increase, rather than a decrease, in Ig-secreting cells was seen following CY treatment. CY-treated MS patients averaged 1380 +/- 535 spontaneous total (IgM + G + A) Ig plaque-forming cells (PFC) per 1 X 10(6) peripheral blood mononuclear cells (MNC), measured at 15-22 days after monthly CY administration, while healthy adults had 280 +/- 47 Ig PFC/10(6) MNC, and MS patients not treated with CY had 300 +/- 43 Ig PFC/10(6) MNC. The observed increase was due to an increase in IgG and IgA PFC. PFC levels remained elevated for 4 weeks following CY treatment, decreasing to control levels by 7-8 weeks post-CY. A small increase in serum IgG level was noted after greater than 12 months of pulse CY therapy; no increase was seen in CSF IgG levels. A preferential decrease in the number of CD4+ T cells was also seen in the CY-treated MS patients. We propose that the observed increase in the number of spontaneous Ig PFC was due to the CY-induced disruption of the CD4+ T cell-mediated control of in vivo activated B cells.

Administration of monthly-pulse cyclophosphamide in multiple sclerosis patients. Effects of long-term treatment on immunologic parameters.

Eleven patients with chronic progressive multiple sclerosis received monthly pulses of cyclophosphamide (CY) for approximately one year. During the final 9 months the monthly dose ranged between 1000 mg/m2 and 2000 mg/m2. This resulted in a marked (47% or greater) reduction in CD4 (T helper/inducer) cells a less striking (22%) decrease in CD8 (T suppressor/cytotoxic) cells and a decline in the CD4/CD8 ratio. The magnitude of the decrease in CD4 cells correlated with the total dose received (r = 0.88, P less than 0.05). B cells were reduced 50% and FcR+ lymphocytes were reduced 48% without comparable reduction in natural killer cells or antibody-dependent cellular cytotoxicity. Proliferative responses to PHA were suppressed. Two patients improved, seven stabilized and two continued to worsen. Monthly pulses of CY can achieve substantial and differential reduction in immune parameters and appear to slow the disease progression in some MS patients.

Administration of monthly pulses of cyclophosphamide in multiple sclerosis patients. Delayed recovery of several immune parameters following discontinuation of long-term cyclophosphamide treatment.

Recovery of various components of the immune system was followed in eight patients with multiple sclerosis who had received monthly pulses of cyclophosphamide (CY) for approximately one year. CD8 cell numbers and NK and ADCC functions recovered in 1-2 months; B cells and FcR+ cell numbers recovered in 2-4 months. The recovery of CD4 cells and total T cell numbers, CD4/CD8 ratio and proliferative responses to PHA took more than 4 months. The impaired proliferation was not attributable to low IL-2 receptor expression. Once immunosuppression has been achieved pulse administration of CY at 2- to 4-month intervals may be feasible for long-term maintenance treatment.

Therapy of acquired immune deficiency syndrome with recombinant interleukin-2.

Recombinant human interleukin-2 (rIL-2) was administered to 87 patients with the acquired immune deficiency syndrome (AIDS) to test the hypothesis that this lymphokine would correct the underlying qualitative and quantitative deficiency in cellular immunity. Patients were divided into two groups by the presence or absence of Kaposi's sarcoma and subjects within each of these groups received intravenous rIL-2 three times weekly for eight weeks. Subjects received one of several doses which ranged from 1,000 to 2,000,000 units per square meter body surface area. Toxicity at high doses consisted of flu-like symptoms and hypotension at highest doses. Partial objective tumor regression was observed in three patients with Kaposi's sarcoma. Seventeen patients had progression of disease (new opportunistic infection or increase in Kaposi's sarcoma) during therapy. No improvement in immunologic status was observed. This study does not suggest a role for single-agent rIL-2 therapy of established AIDS but its use in less symptomatic persons or in conjunction with antiretroviral agents such as azidothymidine should be investigated.

CD8+ lymphocytes can control HIV infection in vitro by suppressing virus replication.

Lymphocytes bearing the CD8 marker were shown to suppress replication of human immunodeficiency virus (HIV) in peripheral blood mononuclear cells. The effect was dose-dependent and most apparent with autologous lymphocytes; it did not appear to be mediated by a cytotoxic response. This suppression of HIV replication could be demonstrated by the addition of CD8+ cells at the initiation of virus production as well as after several weeks of virus replication by cultured cells. The observations suggest a potential approach to therapy in which autologous CD8 lymphocytes could be administered to individuals to inhibit HIV replication and perhaps progression of disease.

Cytosine arabinoside induced changes in natural killer and antibody dependent cellular cytotoxicity functions in multiple sclerosis patients.

Five multiple sclerosis patients were treated weekly with cytosine arabinoside (araC) on an escalating dose schedule. The dose was initiated at 50 mg/M2 and then increased once each week by 50 mg/M2 (unless toxicity caused delay). Dosage decisions were based on whether or not the antibody-dependent cellular-cytotoxicity (ADCC) or natural killer (NK) cytotoxicity levels had been reduced to a level more than 2 standard deviations below the control range. Cytosine arabinoside treatment was discontinued in 2 of 5 subjects at doses of 500 mg/M2 due to toxicity. The 3 remaining patients demonstrated sustained reductions in the percentage of FcR+ cells in their peripheral blood. The maximum percentage reductions from the baseline values ranged from 50% to 76%. Concomitant reductions in the NK activity at the same doses ranged from 65% to 83%. ADCC activity in all 3 patients, however, was relatively resistant to suppression. The nadirs for the ADCC activity were only 16% to 44% below the baseline minimum. AraC was shown to reduce the proportion of FcR+ cells and NK cytotoxic activity in preference to ADCC activity.

Reduced ecto-5'-nucleotidase activity and enhanced OKT10 and HLA-DR expression on CD8 (T suppressor/cytotoxic) lymphocytes in the acquired immune deficiency syndrome: evidence of CD8 cell immaturity.

Markedly reduced ecto-5'-nucleotidase activity was found in peripheral blood lymphocytes from 27 out of 30 homosexual men with the acquired immune deficiency syndrome (AIDS) in association with Kaposi's sarcoma (AIDS-KS; 2.67 +/- 1.70 U/10(6) cells; n = 13), opportunistic infections (AIDS-OI; 9.29 +/- 7.32; n = 7), or the AIDS-related complex (ARC; 9.82 +/- 6.12; n = 10). These values were significantly different from healthy controls (22.70 +/- 4.58; p less than 0.001). In AIDS-KS patients, both T cells and non-T cells exhibited significantly reduced ecto-5'-NT activity (p less than 0.001). AIDS-KS CD8 cells contained 20% of the mean ecto-5'-NT activity (7.04 +/- 3.53) displayed by control CD8 cells (34.07 +/- 4.86; p less than 0.001). No significant difference in enzyme level was observed between control and AIDS-KS CD4 cells (11.93 +/- 4.98 vs 7.98 +/- 3.28, respectively). In AIDS patients, lymphocyte ecto-5'-NT activity was inversely related (r = -0.518; p less than 0.01) to the absolute number of OKT10+ cells, but no correlation was found with the number of HLA-DR+ cells (r =-0.224). Two-color analysis of lymphocytes from AIDS-KS patients revealed that 75 +/- 12% of circulating CD8 cells expressed the OKT10 antigen, whereas only 10 +/- 6% of control CD8 cells did. HLA-DR antigens, which are not normally found on circulating resting T cells, were expressed in AIDS-KS CD8 cells, although to a lesser extent than OKT10. These data demonstrate that most AIDS CD8 cells differ from control CD8 cells. Although it has been suggested that these cells are activated cytotoxic or suppressor cells, the data presented here support the hypothesis they are immature. Reduced T cell ecto-5'-NT activity and enhanced expression of OKT10 and HLA-DR antigens on circulating CD8 cells, in conjunction with lack of transferrin receptor-(OKT9) and IL 2 receptor-(Tac) bearing lymphocytes, sustain this latter hypothesis. The correlation of the numerical reduction of CD4 cells with the reduced levels of ecto-5'-NT (r = 0.606; p less than 0.01) suggests that the abnormal maturation of CD8 cells seen in AIDS might be a consequence of the CD4 deficiency characteristic of this syndrome.

Defective monocyte function in acquired immune deficiency syndrome (AIDS): evidence from a monocyte-dependent T-cell proliferative system.

T-cell proliferative responses to the mitogenic monoclonal antibody anti-Leu 4 were assessed in healthy controls, lymphadenopathy syndrome (LAS) patients, and acquired immune deficiency syndrome (AIDS) patients. While 19% of the control group showed low anti-Leu 4 responses (less than 12,000 cpm), 60% of the LAS patients, 71% of the AIDS-opportunistic infection patients, and 50% of the AIDS-Kaposi's sarcoma patients showed low responses. T-cell responsiveness in healthy low responders was greatly enhanced by the addition of monocytes from an anti-Leu 4 high responder (responder monocytes). We therefore sought to determine if the low-responder state in LAS and AIDS patients was also mediated by monocytes and, thus, correctable by the addition of responder monocytes. In the LAS low-responder group, the level of enhancement by healthy responder monocytes was similar to that observed for the healthy low-responder group. In the AIDS low-responder group, however, the level of enhancement was significantly lower than that observed in the healthy low-responder and LAS low-responder groups. These findings suggest that impaired proliferation to anti-Leu 4 in LAS patients may be due to a monocyte defect similar to the monocyte defect responsible for low anti-Leu 4 responses in healthy controls. AIDS patients, however, show additional defects in anti-Leu 4-induced proliferation that are not fully corrected by the addition of responder monocytes.

Suppression of natural killer cell activity by Friend murine leukemia virus.

BALB/c mice infected with Friend murine leukemia virus (F-MuLV) evinced a decreased natural killer (NK) cell activity to susceptible target cells. This suppression increased as the interval between infection and assay was lengthened. The decrease in NK activity due to F-MuLV infection was partially reversible when spleen cells were pretreated with interferon before the cytolytic assay. The ability of F-MuLV-infected splenocytes to bind to target cells was unaltered, indicating that the defect was in the lytic phase of NK cytolysis. When mixed with uninfected spleen cells, F-MuLV-infected splenocytes suppressed their NK cell activity. This suppression was associated with a nylon wool-adherent cell population in the F-MuLV-infected spleens.