Frequency of cytokine-producing T cells in HIV-infected patients treated with stavudine, didanosine, and ritonavir

To assess prospectively the influence of the control of viral replication on the frequency of cytokine-producing T cells, and to correlate these changes with immune activation, we conducted a 15-month follow-up study of IFN-gamma- and IL-2-producing CD4+ and CD8+ T cells at a single-cell level in 12 previously untreated patients receiving highly active antiretroviral therapy (HAART). At baseline we observed a strikingly high proportion of IFN-gamma-producing CD8+ T cells. The treatment-induced decrease in the proportion of IFN-gamma-producing CD8+ T cells ran parallel to the decrease in HLA-DR+ and CD38+CD8+ T cell subsets and was associated with the reduction in HIV RNA level. IL-2-producing cells were mainly CD4+. As a consequence of CD4+ T cell loss, the number of IL-2-producing CD4+ T cells was lower in patients than in control subjects (52 vs. 171 cells/microl), but the proportion of these cells was unchanged (22.4 vs. 19.3). During therapy the proportion of CD4+ IL-2-producing cells was initially stable and then fell markedly at month 5, followed by a gradual return to previous values. The reduction in viral load was associated with the fall in the proportion of CD4+ activated subsets. Intracellular cytokine assays are a new approach to the assessment of T cell function in HIV infection. Our results suggest that the functional capacity of CD4+ T cells is probably less severely altered than previously thought on the basis of conventional assays. CD8+ T cells exhibit an increased capacity to produce IFN-gamma that is associated with an increase in activation marker expression. These alterations decrease partially and in parallel under treatment.

[Antiretroviral therapy and immune reconstitution]

The course of the HIV infection has been dramatically modified since the introduction of highly active antiretroviral therapy (HAART) combining inhibitors of the HIV-1 reverse transcriptase and protease. Despite some controversies about the extent to which the immune system can normalize, it is generally admitted nowadays that a numerical and functional CD4 cell profile more akin to asymptomatic HIV-infected individuals can be restored in AIDS patients and can confer host protection against opportunistic events. The best hallmark of such immune restoration is the massive decline in the mortality and morbidity related to AIDS that have been registered in all industrialized countries. These changes involve a recirculation of mature peripheral T cells, a regeneration of naive T cells from thymic origin and a restoration of memory CD4 T cell réactivities. Although these recent advances warrant increased optimism, HAART by reducing the virus burden is unable to restore immunity against HIV itself, except when introduced at the very early stage after virus inoculation. The single condition required for immune reconstitution is an efficient and durable inhibition of virus replication. These positive effects can be obtained at late stages of the disease even when the patients have been heavily pre-treated. They also demonstrate that HIV does not definitively alter the lymphoid tissues nor the immune defenses, even aller years of infection and severe immune suppression, except for HIV-specific CD4 T helper cells.

T cell changes after combined nucleoside analogue therapy in HIV primary infection

OBJECTIVE

To characterize the immune changes after treatment of acute HIV-1 infection with triple nucleoside analogue therapy.

DESIGN

Immunological and virological parameters were monitored from day 0 to weeks 36-44 in eight patients [median CD4 cells = 451 cells/microl (range: 149-624), viral load = 4.8 log10 copies/ml (range: 6.5-3.3)] who started at time of primary HIV infection (PHI) a therapy including zidovudine (ZDV), didanosine (ddl), and lamivudine (3TC).

METHODS

Lymphoid subsets were evaluated on peripheral blood lymphocytes by four-colour flow cytometry using a panel of mAbs directed against differentiation and activation markers.

RESULTS

We observed a median -2.1 (range: -1; -3.3) log10 copies/ml viral load decrease and a median +158 cells/microl (range: +7 to +316) CD4 cell count increase at week 4 reaching normal CD4 cell count values of 761 CD4 cells/microl (range: 389-1153) at weeks 36-44. Virus undetectability was obtained at week 24 for all subjects. A rapid CD4 T cell amplification involved both memory and naive CD4 T cells. This was associated with a very rapid and significant decrease in activation markers [human leukocyte antigen-DR (HLA-DR), CD38] on both CD4 and CD8 T cell subsets together with a CD8+CD28+ cell increase as early as week 4.

CONCLUSIONS

These results show that early therapy with nucleoside analogues can correct the immunological abnormalities observed in CD4 and CD8 T cell subsets at the time of PHI. This early kinetics in T cell recovery appears to be faster than in established disease.

Restoration of the immune system with anti-retroviral therapy

Clinical benefits of highly active anti-retroviral treatments (HAART) are increasingly evidenced by resolving opportunistic infections and malignancies, as well as declining hospitalization and mortality rates [1]. This suggests that potent and sustained suppression of viral replication, at least to some extent, is associated with reconstitution of the immune system even in adult patients treated at advanced stages of the disease. Increased susceptibility to opportunistic infections and tumors mainly results from the loss of memory CD4+ T cell reactivity against recall antigens which is an early event in HIV disease progression. Primary responses of naive CD4+ T cells against new pathogens are suppressed even earlier in the course of HIV disease, and the progressive depletion in naive CD4+ T cells reflects profound alterations in T cell regeneration capacities. Previous studies revealed that monotherapy with ritonavir, a protease inhibitor, resulted in a slight improvement in memory CD4+ T cell responses to recall Ags only when detectable prior to onset of therapy, suggesting that the loss of CD4+ T cell reactivity might be irreversible at advanced stages of the disease [2]. In contrast our group demonstrated more recently that restoration in CD4+ T cell reactivity to specific antigens was feasible when HAART was administered in progressors [3]. Here we address some of the questions raised by immune restoration with HAART when administered at advanced stages of the disease.

Positive effects of combined antiretroviral therapy on CD4+ T cell homeostasis and function in advanced HIV disease

Highly active antiretroviral therapy (HAART) increases CD4(+) cell numbers, but its ability to correct the human immunodeficiency virus (HIV)-induced immune deficiency remains unknown. A three-phase T cell reconstitution was demonstrated after HAART, with: (i) an early rise of memory CD4(+) cells, (ii) a reduction in T cell activation correlated to the decreasing retroviral activity together with an improved CD4(+) T cell reactivity to recall antigens, and (iii) a late rise of "naïve" CD4(+) lymphocytes while CD8(+) T cells declined, however, without complete normalization of these parameters. Thus, decreasing the HIV load can reverse HIV-driven activation and CD4(+) T cell defects in advanced HIV-infected patients.

Reductions in viral load and increases in T lymphocyte numbers in treatment-naive patients with advanced HIV-1 infection treated with ritonavir, zidovudine and zalcitabine triple therapy

In order to test the hypothesis that a combination of protease inhibitors with nucleoside analogues-agents known to inhibit different steps of the human immunodeficiency virus (HIV) life cycle--is likely to prove more effective in reducing viral loads than either of those modalities alone, we performed a 60 week, open-label trial in 32 HIV-positive patients with depressed CD4 T lymphocyte cell counts but no active AIDS-defining illnesses. For the first 2 weeks, patients received 600 mg twice daily of liquid ritonavir, a protease inhibitor; then zidovudine 200 mg three times daily and zalcitabine 0.75 mg three times daily were added to the treatment regimen. Mononuclear blood cell fractions were analysed for infected cell levels, using a co-culture system. HIV-1 RNA in plasma was measured both by reverse transcriptase-polymerase chain reaction (RT-PCR) and reverse transcriptase quantitative PCR (QcRT-PCR); lymphocyte counts were determined by standard laboratory methods. In the 2 weeks of ritonavir therapy, both the mean count of infectious blood cells and plasma HIV RNA levels decreased dramatically. Mean CD4 cell counts increased from 173 cells/mm3 at baseline to 286 cells/mm3; CD8 cell counts rose from 951 cells/mm3 to 1,141 cells/mm3. With the introduction of the nucleoside analogues, infectious cell counts and plasma virus dropped another log unit to a nadir at 8 weeks, while CD4 T lymphocyte counts continued to rise slowly. By week 28, 12 patients had withdrawn due to adverse events, none of which were life-threatening. At week 36, infectious material could not be detected in the cells of 10 of the 17 remaining patients; by week 60, four of the seven patients with residual viraemia at week 24 had undergone viral relapse. After the introduction of a more palatable capsule formulation of ritonavir at week 52, infectious cells and plasma virus were undetectable in 50-60% of patients. The combination of protease inhibitors and nucleoside analogues significantly reduces HIV load, and in some patients may suppress viral activity for sustained periods.

Dynamics and modulation of human immunodeficiency virus type 1 transcripts in vitro and in vivo

The dynamics of human immunodeficiency virus type 1 (HIV-1) transcription was analyzed in vitro and in vivo by using a specific molecular approach which allows accurate quantitation of the different classes of viral mRNAs. Unspliced (US) and multiply spliced (MS) HIV-1 transcripts were assayed by competitive reverse transcription (cRT)-PCR, using a single competitor RNA bearing in tandem internally deleted sequences of both template species. Acute HIV-1 infection of primary peripheral blood mononuclear cells (PBMCs), monocytes/macrophages cells, and the A3.01 T-lymphocyte-derived cell line was studied; both classes of HIV-1 mRNAs increased exponentially (r2 > 0.98) at days 1 to 3 and 1 to 4 postinfection in HIV(IIIB)-infected A3.01 cells and PBMCs, respectively, whereas monocytes/macrophages infected with monocytotropic HIV(BaL) exhibited a linear (r2 = 0.81 to 0.94) accumulation of US and MS transcripts. Following induction of chronically infected ACH-2 cells, MS transcripts increased 2 h postinduction and peaked at 5 h (doubling time, 58 min), while at 24 h, US mRNAs increased 3,053-fold compared with basal time (doubling time, 137 min). To address the biopathological significance of HIV-1 expression pattern during infection progression, pilot cross-sectional and longitudinal analyses were carried out with samples from untreated and treated HIV-1-infected patients. In almost all untreated (recently infected, long-term nonprogressor, and progressor) patients, MS transcript levels followed the general trend of systemic HIV-1 activity. In patients under treatment with powerful antiretroviral compounds, viral MS transcripts rapidly fell to undetectable levels, indicating that in vivo, levels of MS mRNAs in PBMCs are closely associated with the number of newly infected cells and suggesting a new role for the quantitative analysis of HIV-1 transcription in infected patients.

Infectious amplification of wild-type human immunodeficiency virus from patients' lymphocytes and modulation by reverse transcriptase inhibitors in vitro

The relative in vitro potency of nine human immunodeficiency virus (HIV) type 1 reverse transcriptase inhibitors was evaluated in a coculture assay which measures the frequencies of infectious primary cells from HIV-positive patients by the limiting dilution technique and measures their apparent reduction under increasing concentrations of drugs. An advantage of this assay is that it utilizes a variety of wild-type viruses not selected by in vitro propagation. Potency ranking placed the (-)-L-enantiomer of 2',3'-dideoxy-5-fluoro-3'-thiacytidine [(-)-FTC], an oxathiolane pyrimidine nucleoside analog (90% effective concentration = 55 nM), before 2',3'-dideoxycytidine (DDC) (74 nM), (-)-2',3'-dideoxy-3'-thiacytidine (3TC) (300 nM), 3'-azido-3'-deoxythymidine (AZT) (530 nM), TIBO R82913 (670 nM), and 2',3'-dideoxyinosine (DDI) (6,400 nM). HIV from AZT-naive patients' lymphocytes was more sensitive to the inhibitory effect of (-)-FTC, 3TC, or DDC than was highly AZT-resistant HIV obtained from AZT-treated patients' cells, indicating partial cross-resistance between thymidine and cytidine analogs. Combined inhibitory concentrations of AZT with (-)-FTC, 3TC, DDC, and DDI produced synergistic interactions as determined by the multiple-drug effect analysis. Synergistic interactions were demonstrable with AZT plus (-)-FTC or with AZT plus DDC with cells bearing AZT-resistant HIV. The inhibitory concentrations of AZT established by this cell-to-cell virus transmission assay are closer than those determined by the conventional assay system to the extracellular AZT concentrations required in patients' plasma to achieve comparable levels of HIV inhibition in vivo.

The effect of treatment with zidovudine with or without acyclovir on HIV p24 antigenaemia in patients with AIDS or AIDS-related complex

OBJECTIVE

To evaluate changes in serum HIV p24-antigen levels in a subset of patients who participated in a European/Australian double-blind, placebo-controlled trial evaluating the efficacy of zidovudine (250 mg every 6 h) alone or in combination with acyclovir (800 mg every 6 h) in patients with AIDS, AIDS-related complex (ARC) or Kaposi's sarcoma (KS).

DESIGN

Double-blind, placebo-controlled randomized clinical trial of less than or equal to 6 months' therapy.

SETTING

Samples were obtained from patients attending teaching hospital outpatient clinics in seven European countries and Australia.

SUBJECTS

One hundred and ninety-seven HIV-infected patients (60 with AIDS and 137 with ARC or KS).

MAIN OUTCOME MEASURES

Serum HIV p24-antigen levels measured using the Abbott HIV solid-phase enzyme immunoassay.

RESULTS

Of 76 ARC/KS patients who were initially HIV p24-antigen-positive, one out of 25 randomized to placebo, eight out of 23 to zidovudine and 11 out of 28 to the zidovudine/acyclovir combination became antigen-negative. The proportion of patients who became antigen-negative was significantly higher in both the zidovudine group (P = 0.016) and the zidovudine/acyclovir group (P = 0.004), compared with the placebo group. There were no statistical differences between the zidovudine and the zidovudine/acyclovir groups. During the trial p24-antigen levels in the zidovudine-treated patients reached their minimum after 4-8 weeks of therapy, and tended to increase gradually thereafter. Disease progression occurred irrespective of whether p24-antigen levels declined during therapy. No association between p24-antigen responses to therapy and baseline disease stage, Karnofsky score or baseline CD4 cell count was detectable.

CONCLUSION

Acyclovir does not potentiate the effect of zidovudine on p24-antigen levels. Change in antigen level in response to antiviral therapy needs further investigation before it is used as a surrogate marker for clinical efficacy of antiviral therapy.

Cystatin C levels in sera of patients with human immunodeficiency virus infection. A new avidin-biotin ELISA assay for its measurement

A solid-phase enzyme-linked immunosorbent assay (ELISA) for determining human serum cystatin C is described. In 50 normal samples, cystatin C concentration was 1247 +/- 224 micrograms/L (mean +/- SD) which is in agreement with previously reported levels. Serum levels of cystatin C and beta 2-microglobulin (beta 2-M) were investigated in a time-course study during the development of human immunodeficiency virus (HIV) infection. We found a persistent and uniform increase in the beta 2-M concentration (2762 +/- 1239 micrograms/L). In contrast to beta 2-M, on the basis of cystatin C levels, we found two distinct populations, one of which demonstrated an increased concentration (1620 +/- 618 micrograms/L). Interestingly a second group (21% of patients) exhibited an initial significant decrease in cystatin C concentration with a mean value of 377 (range 55-850) micrograms/L, followed by an increase. The biphasic pattern of cystatin C serum, a major cysteine proteinase inhibitor, during the course of HIV infection suggests a possible role for these proteinases (or proteinase inhibitors) in the development of this syndrome.

Productive human immunodeficiency virus infection levels correlate with AIDS-related manifestations in the patient

Mononuclear cells were obtained from 71 human immunodeficiency virus type 1 (HIV-1) seropositive subjects presenting and first visit either as asymptomatic or with minor symptoms and with CD4 lymphocytes greater than 550 per mm3 (group A, 35 patients) or as patients with AIDS, AIDS-related illnesses, or CD4 lymphocytes less than 400 per mm3 (group B, 36 patients). After 1-5 years of follow-up, 13 patients of group A had essentially retained their initial status (asymptomatics); the 22 others had suffered clinical or immunological deterioration (progressors). Frozen cells were thawed and submitted to lethal gamma-irradiation in vitro (4500 rads; 1 rad = 0.01 Gy) before they were cultured with normal phytohemagglutinin-stimulated lymphocytes to determine radiation-resistant HIV expression ex vivo (R-HEV). HIV antigenemia correlated with R-HEV values in 142 samples (r = 0.92, P less than 0.001) but was a less sensitive predictor of disease than R-HEV. R-HEV was detected in all specimens from patients with major AIDS-related illnesses or HIV-associated CD4 lymphopenia. In 77% of the progressors from group A, R-HEV detection preceded the onset of AIDS-associated disease or CD4 lymphopenia by 1 year (average). Conversely, R-HEV was low or was not detected in 36 sequential specimens from the 13 patients who remained asymptomatic over the following 2-5 years. Thus, persistently low HIV expression in vivo predicted a nondiseased state, whereas higher HIV expression levels seemed necessary for disease to occur. These data indicate that R-HEV is related to productive HIV infection in vivo, the latter acting as a determinant of AIDS-related illnesses. In view of this, measurement of HIV expression levels in the patient should be useful in antiviral efficacy trials.

Immunohistochemical evidence for human immunodeficiency virus-1 infection of liver Kupffer cells

To investigate the possibility of human immunodeficiency virus-(HIV) 1 infection of liver cells, liver samples from 17 patients with either acquired immunodeficiency syndrome (AIDS, 13), AIDS-related complex (ARC, 3), or lymphadenopathy syndrome (LAS, 1) were studied. A monoclonal antibody directed against the p24 gag HIV-1 protein was used in an immunoperoxidase assay and yielded positive results in seven out of 17 samples. Staining by anti-p24 antibody was of three types: diffuse in Kupffer cells of most samples, inside granuloma in cells that were probably histiocytes, and in some sinusoidal cells whose origin was difficult to ascertain. Attempts to locate the CD4 membrane antigen showed that it was mainly present on endothelial sinusoidal cells. These results indicate that liver cells, including Kupffer cells, might be infected by HIV-1, and that these cells might be involved in certain liver lesions observed during HIV-1 infection, particularly sinusoidal abnormalities.

HTLV-III in cells cultured from semen of two patients with AIDS

Epidemiological results suggest that the etiological agent of the acquired immune deficiency syndrome (AIDS) is transmitted primarily through blood products, semen, and saliva. There is evidence that the human T-cell leukemia (lymphotropic) virus type III (HTLV-III) is this agent. HTLV-III has been isolated repeatedly from T cells obtained from peripheral blood or lymph node tissue of AIDS and pre-AIDS patients and of healthy people believed to have been exposed to the virus. In the present study, HTLV-III was detected in and isolated from T cells present in the seminal fluid of AIDS patients. Mononuclear cells from the semen of AIDS patients and normal individuals were cultured in the presence of T-cell growth factor (interleukin-2). After 6 to 8 days, HTLV-III antigens were transiently expressed by the cells from the AIDS patients but not by those from the normal individuals. When the mononuclear cells from the semen of AIDS patients were cocultured with a permissive human T-cell line, cell cultures were produced that expressed high levels of reverse transcriptase activity, showed retroviral particles by electron microscopy, and were positive for HTLV-III-specific antigens when tested by fixed-cell indirect immunofluorescence with the use of monoclonal antibodies to the p24 and p15 antigens of HTLV-III.

Isolation of human T-cell leukemia virus in acquired immune deficiency syndrome (AIDS)

Several isolates of a human type-C retrovirus belonging to one group, known as human T-cell leukemia virus (HTLV), have previously been obtained from patients with adult T-cell leukemia or lymphoma. The T-cell tropism of HTLV and its prevalence in the Caribbean basin prompted a search for it in patients with the epidemic T-cell immune deficiency disorder known as AIDS. Peripheral blood lymphocytes from one patient in the United States and two in France were cultured with T-cell growth factor (TCGF) an shown to express HTLV antigens. Virus from the U.S. patient was isolated and characterized and shown to be related to HTLV subgroup I. The virus was also transmitted into normal human T cells from umbilical cord blood of a newborn. Whether or not HTLV-I or other retroviruses of this family with T-cell tropism cause AIDS, it is possible that patients from whom the virus can be isolated can also transmit it to others. If the target cell of AIDS is the mature T cell as suspected, the methods used in these studies may prove useful for the long-term growth of these cells and for the identification of antigens specific for the etiological agent of AIDS.

Mechanism of action of the C4 nephritic factor. Deregulation of the classical pathway of C3 convertase

Three mechanisms that regulate the formation and function of the classical pathway C3 convertase (C4b2a) have been elucidated: (a) an intrinsic decay of the enzyme that is temperature dependent; (b) an extrinsic decay mediated by the effect of the serum protein C4b binding protein (C4-bp); and (c) inactivation of C4b by the proteolytic action of C4b/C3b inactivator (C4b/C3bINA), which cleaves that alpha' chain of C4b to yield C4d (alpha 2) and C4c (alpha 3, alpha 4, beta, and gamma chains). A fourth mechanism described here is based on the observation that the IgG fraction of the serum of certain patients with glomerulonephritis contains a protein termed C4 nephritic factor (NFc), which prevents the intrinsic decay of C4b2a. This protein, which prolongs the half-life of surface-bound C4b2a from 7.5 min to greater than 5 h, increases the use of C3 and C5. It also inhibits the decay produced by C4-bp by preventing the dissociation of C2a from the C4b2a complex. Additionally, the C2b/C3bINA alone, or in the presence of C4-bp, fails to cleave the alpha' chain of C4b in the surface-bound stabilized C4b2a complex. This protective property of NFc requires the presence of C2a, because C4b was not protected unless it was bound to C2a. Thus in the presence of NFc, the three natural controls of the function of the classical pathway convertase, intrinsic decay, extrinsic decay, and proteolytic cleavage, are bypassed.

[Immune complex nephropathy and hereditary deficiency of C1 esterase inhibitor (author's transl)]

Deficiency of C1 esterase inhibitor (C1-INH) was demonstrated in 7 of 22 subjects belonging to the same French family. Immune complex glomerulonephritis without lupic symptoms was discovered in one of the C1-INH deficient subjects, and in a girl of the same family the same deficiency was associated with an insulin-dependent diabetes of sudden onset. The pathophysiological consequences of complement deficiency resulting from the lack of C1 esterase inhibitor are discussed.

Clq deposits at the dermoepidermal junction: a marker discriminating for discoid and systemic lupus erythematosus

Discoid lupus (DL) and systemic lupus erythematosus (SLE) patients have been comparatively evaluated for complement and immunoglobulin deposits at the dermoepidermal junction (DEJ) by immunofluorescence (IF). When IF was positive, Clq deposits were quasi-constantly found in SLE patients with or without skin lesions (90%), while Clq was found in only 29% of the DL patients. Of the 42 DL patients followed-up to at least 2 years, 4 have eventually evolved a systemic disease. In these 4, neither cryoglobulinemia nor significant titers of ANA had been found at the time of presentation. Only 1 of these 4 patients had initially circulating immune complexes (P.E.G) and a positive IF in a normal sunprotected area. Clq deposits at the DEJ were present in all these 4. Of the remaining 38 DL patients, none has progressed to SLE: 8 had had significant titers of ANA, 5 had had circulating immune complexes, and 3 others had had cryoglobulinemia. Thus Clq deposits in DL cases are associated with a relatively high incidence of eventual systemic disease. Taken together, these data suggest that Clq deposits in skin may be a marker for systemic lupus.

Systemic lambda light-chain deposition in a patient with myeloma

Systemic lambda light-chain deposition occurred in a 73-year-old man with myeloma. An initial renal biopsy specimen showed the features of myeloma kidney. When he died 22 months later lambda light chains were detected by immunofluorescence in kidneys, liver, spleen, and heart. They were probably responsible for cardiac dysfunction and the fatal arrhythmia. It is suggested that in this patient deposition was due to a structural alteration of the light chains, possibly induced by cyclophosphamide.

In vitro characteristics on human lymphocyte functions of a new immunomodulatory agent, a cyclic peptide, cyclomunine

Cyclomunine, a cyclic peptide extracted from Fusarium equisiti, inhibits responses of human lymphocytes to mitogens, soluble antigens and allogeneic cells and the proliferation of lymphoblastoid cell lines. Cyclomunine has little effect on small lymphocytes but acts rather on lymphoblasts. It has no effect on fibroblasts and myeloid cells. Cyclomunine partially inhibits the generation of suppressor cells induced by Con A and the generation of cytotoxic T cells in a mixed lymphocyte culture and totally inhibits the in vitro synthesis of Ig by PBL. Cyclomunine merits consideration as a new in vitro anti-lymphoblastic agent.

[Treatment of severe systemic lupus erythematosus. Long-term results in 55 patients (author's transl)]

Out of 55 patients with severe systemic lupus erythematosus (SLE) retrospectively studied from 1962 to 1979, 32 had diffuse proliderative glomerulonephritis and 23 had one or several extrarenal and/or haematological manifestations of the disease. All received corticosteroids in high dosage (0,8 to 1,5 up period was 48 months from the beginning of treatment. The actuarial survival rates for the whole groupe after 1,5 and 10 years were 92,4%, 83,4% and 77,2% respectively. Eight patients died: 5 of SLE and 3 of iatrogenic complications. Four are kept alive by maintenance haemodialysis. At the end of the study period, SLE was quiescent in 37 patients, including 14 who had discontinued corticosteroids for 5 to 72 months. The five-year survival rates were very similar in patients with renal and extrarenal involvement (86,4% and 81,6% respectively). In the latter group myocardial insufficiency, thrombopenia and thromboembolic complications were the main factors of morbidity and mortality. Corticosteroids were administered alone to 25 patients and in combination with cyclophosphamide to the remaining 30. Cyclophosphamide was given initially in 13 cases or subsequently on account of intolerance (7 cases) or resistance (10 cases) to steroids. Similar results were obtained with these two therapeutic regimens, but it must be noted that cyclophosphamide was mainly used in the more severe forms of SLE.

Nephritic factor of the classical pathway of complement: immunoglobulin G autoantibody directed against the classical pathway C3 convetase enzyme

A factor, functionally characterized by its capacity to stabilize the normally labile classical pathway C3-converting complex of the classical pathway of complement, has been isolated from the serum of one patient with a case of acute glomerulonephritis, subsequent to a cutaneous infection. The factor confers long-lived stabilization of classical pathway C3 convertase complexes formed both in the solid (sensitized sheep erythrocytes bearing activated C1 and the classical pathway C3 convertase) and fluid phase. The half-life of such stabilized C3-cleaving enzymes extended beyond several hours at 37 degrees C. The stabilizing activity was associated with a protein fraction immunochemically identified as immunoglobulin (Ig)G, a sizeable population of which exhibited a gamma chain of 60,000 daltons. The IgG-associated stabilizing activity was found to bind to the classical pathway C3 convertase enzyme via a fragment bearing the antigen-binding site of the molecule [F(ab)(2) and F(ab)]. Such binding was demonstrable for classical pathway and not for alternative pathway C3 convertase. Thus, the stabilizing factor behaves like an autoantibody to the C3-converting complex of the classical pathway of complement. The binding of the antibody to the enzyme affords protection of the latter against decay-degradation. By analogy with the nephritic factor of the alternative pathway situation where IgG autoantibodies specifically bind to alternative pathway C3 convertase enzymes and protect them from degradation, the functionally unusual IgG in our patient was designated as the nephritic factor of the classical pathway. Indirect evidence suggests that nephritic factor of the classical pathway-IgG might be of the IgG3 subclass.

The dense deposits disease of the renal basement membranes

Dense-deposits disease is characterized by an original morphological aspect of the renal basement membranes which have an electron-dense appearance. The immunofluorescence studies showed C3 alone in kidney. Low serum C3 levels and the presence of C3 NF activity have been detected in this disease, demonstrating an activation of the complement alternative pathway. The observation of recurrence in transplanted kidneys contributed to establish the sequence of the morphological events and showed the dissociation between the serological complement profiles and the lesions. Although the nature of the dense deposits remains still unknown, the altered membranes are recognized by at least some anti-GBM antibodies.

Recurrence of dense deposits in transplanted kidneys: I. Sequential survey of the lesions

Serial specimens from transplanted kidneys were obtained in 11 patients with dense deposit disease (DDD). The recurrence of DDD was obvious in 9 patients and appeared very early after grafting. Three different types of evolution of the lesions were observed. In 4 patients no modification of the lesions occurred with time, and in 2 of them the dense alteration alone persisted without any other glomerular changes. In 3 patients a progression of the lesions was observed, whereas a regression occurred in 1 other patient. From these observations the following sequence of the morphologic changes can be proposed: the dense alteration appears first and constitutes the specific marker of that disease; the C3 deposition in the kidney occurs later following the appearance of the dense lesion.

Recurrence of dense deposits in transplanted kidney: II. Serum complement and nephritic factor profiles

Dense deposit disease of the kidney is a rare form of chronic glomerulonephritis frequently associated with serum complement abnormalities (low C3 levels) and a circulating C3 convertase activator of the alternative pathway, the C3 nephritic factor (NF). Eleven patients with end-stage dense deposit disease underwent kidney transplantation. Of the 11, 7 had pretransplant low C3 and NF. In the posttransplant period, persisting low C3 levels were associated with persisting NF, although not quantitatively so. The original glomerular lesion recurred in the graft within 6 months in 9 of 11. Of these 9, 2 had no complement abnormalities either prior to or after transplantation. Pretransplant complement abnormalities were rapidly corrected in 4 of 7 patients whether or not recurrence of the original lesion occurred. Thus, serum complement profiles before and after transplantation are neither predictive nor indicative of recurrence.

[Description of an unusual enzymic activity cleaving the third component of complement]

A large enzymatic complex cleaving C3 (C3'ase) in the absence of magnesium (EDTA) has been partially characterized in two patients. On gel filtration EDTA-C3'ase was found in an 800 000 fraction containing antigenic C4, IgA and IgG in addition to alpha-2-macroglobulin and IgM normally present. EDTA-C3'ase was specifically neutralized by antibodies to IgG, IgA and C4. The characteristics of this unusual enzymatic complex are compatible with that of a C4b2a complex stabilized by its specific binding to an auto-antibody of the IgG and/or IgA class.