Studies of interferon production and natural killing by lymphocytes from multiple sclerosis patients

Interferons in relapsing-remitting multiple sclerosis: are there benefits from long-term use?

Multiple sclerosis (MS) is one of the most common chronic neurological diseases in young adults in western countries. An important aspect of treatment of this disease is the use of interferons (IFNs). These are molecules with antiviral, immunomodulatory, antiproliferative and hormonal activities. IFNbeta, a class I IFN, has been used extensively in the therapy of MS, particularly in its relapsing-remitting (RRMS) phase, the most frequent clinical form of the disease. Although the available evidence from published clinical trials is difficult to evaluate because of methodological differences, an unbiased review of the data reveals sufficient evidence to conclude that treatment with IFNbeta in RRMS is both efficacious and safe, at least over the periods so far investigated (up to 4-6 years). While there is no reason to suspect that IFNbeta should not continue to be efficacious and safe over the longer term, studies investigating these questions over longer periods and including greater numbers of patients are needed.

Phenotype analysis of unstimulated lymphocytes and anti-CD3-stimulated proliferating T-cells from cerebrospinal fluid and peripheral blood in patients with multiple sclerosis and other neurological diseases

In 15 patients with multiple sclerosis (MS) and in 11 patients with other neurological diseases (OND), the phenotype of fresh unstimulated CSF and PB mononuclear cells and of "in vitro" expanded T-cells was studied by monoclonal antibody stain and cytofluorimeter analysis. A compartment-specific decrease of CD8+Leu8+ and CD8+Leu8- cells in CSF was detected; moreover, lower levels of CD8+Leu8- cells were seen in MS than in OND patients, both in CSF and in PB. Although the percentages of unstimulated CSF CD4+ cells did not differ between MS and OND, a higher proportion of "in vitro" expanded CD4+ T-cells was obtained from MS patients than from OND. Among MS patients, T-cell growth was very scarce or absent in those sampled during relapses. The results suggest alterations both within the CD4+ "helper" and the CD8+ "suppressor-cytotoxic" populations in the CSF of MS patients, and stress the relevance of functional analysis in conjunction with phenotype studies.

Monocytes in active multiple sclerosis: intact regulation of HLA-DR density in vitro despite decreased HLA-DR density in vivo

HLA-DR expression on circulating monocytes varies as a function of disease activity in patients with multiple sclerosis (MS), a putative immunopathological demyelinating disorder. Specifically, monocytes isolated from subjects with active MS exhibit reduced HLA-DR antigen density, and immunoregulatory aberrations such as impaired T lymphocyte-mediated suppression correlate strongly with this quantitative defect. To address the mechanism underlying this phenomenon, we compared in vitro regulation of HLA-DR by interferon beta (IFN beta), interferon gamma (IFN gamma), and lipopolysaccharide (LPS) in monocytes from patients with stable and active MS and normal individuals. Interferon-gamma and LPS enhanced monocyte expression of HLA-DR equally in both MS patient groups, suggesting that underexpression of HLA-DR in active MS was not explained by impaired in vivo monocyte responsiveness. Furthermore, interferon regulation of HLA-DR in normals and stable MS subjects was indistinguishable, indicating that aberrant interferon-mediated regulation of class II major histocompatibility complex (MHC) on circulating monocytes does not appear to be a characteristic of the MS disease state.

Double blind study of intrathecal beta-interferon in multiple sclerosis: clinical and laboratory results

Sixteen patients with clinically definite MS admitted to a double blind randomised controlled trial of intrathecal natural beta-IFN were followed for a mean of 22 months including the six month treatment period. Clinical response, evaluated in terms of relapse frequency and of progression rate, showed an increase in relapse rate in treated patients during the six month treatment period and, overall, no benefit in treated versus placebo patients. Serial evaluations were made of cerebrospinal fluid (CSF) cells, IgG, myelin basic protein and CSF and blood T-cell subsets. A rise in CSF IgG Index, MBP and DR+ cells in IFN-treated patients suggested an activation of intrathecal immune response in treated patients.

Natural killer cells and autoimmunity

In various autoimmune diseases it appears that NK activity is impaired, and that this phenomenon is significant in disease development. Impairment of NK activity may be the result of two different mechanisms. In systemic autoimmune diseases, in which various target organs are involved (nonorgan-specific), the peripheral blood NK level is generally lower than normal. This most likely allows the expression of autoimmune phenomena such as B cell hyperactivity and polyclonal antibody production, as is seen in SLE, due to a defect in the termination of the immune response. In autoimmune diseases with more localized, organ-specific lesions one can detect increased NK activity at the target organ itself. In these instances, the cytotoxic characteristic of the NK cell is more prominent. This theory explains why both increased and decreased NK activity may be observed in autoimmune diseases. In some disorders in which decreased NK activity was suspected of being crucial, immunomodulators, known to increase NK activity, were administered. Yet it is still difficult to separate the NK activity from the effect of the remaining immune system.

PHA-induced interferon in multiple sclerosis: association between gamma interferon and clinical and genetical variables

Gamma interferon (INF-gamma) production, after PHA stimulation of peripheral blood mononuclear cells, from multiple sclerosis (MS) patients with the acute remitting and chronic progressive forms, in attack and remission phases, and from normal controls, was studied by immunoradiometric assay. MS patients in all these 4 clinical states of disease produced less INF-gamma (log value range from 2.55 to 2.65). MNC from the total MS patients produced significantly low levels of INF-gamma compared to the control group (log values 2.60 vs. 2.82; P = 0.001). No association between the interferon production and antigens at any HLA locus (A, B, C, Dw and Bf) was found. There was no correlation between IFN-gamma production and age, sex, duration of disease, or disability index. However there was a slight tendency to negative correlation with the progression index of the disease. The results suggest that this lower IFN-gamma production in MS may be secondary to the disease, and the primary defect may be a severe reduction of the essential lymphocyte populations required for an effective lymphokine cascade to produce the normal immune response against infection.

Biology of natural killer cells

Studies of cytotoxicity by human lymphocytes revealed not only that both allogeneic and syngeneic tumor cells were lysed in a non-MHC-restricted fashion, but also that lymphocytes from normal donors were often cytotoxic. Lymphocytes from any healthy donor, as well as peripheral blood and spleen lymphocytes from several experimental animals, in the absence of known or deliberate sensitization, were found to be spontaneously cytotoxic in vitro for some normal fresh cells, most cultured cell lines, immature hematopoietic cells, and tumor cells. This type of nonadaptive, non-MHC-restricted cellmediated cytotoxicity was defined as “natural” cytotoxicity, and the effector cells mediating natural cytotoxicity were functionally defined as natural killer (NK) cells. The existence of NK cells has prompted a reinterpretation of both the studies of specific cytotoxicity against spontaneous human tumors and the theory of immune surveillance, at least in its most restrictive interpretation. Unlike cytotoxic T cells, NK cells cannot be demonstrated to have clonally distributed specificity, restriction for MHC products at the target cell surface, or immunological memory. NK cells cannot yet be formally assigned to a single lineage based on the definitive identification of a stem cell, a distinct anatomical location of maturation, or unique genotypic rearrangements.