Immune complexes, rheumatoid factors, and cellular immunological parameters in patients with giant cell arteritis

Current concepts in giant cell (temporal) arteritis

Giant cell (temporal) arteritis continues to be a sight-threatening, systemic vasculitis with a poorly understood pathogenesis. The characteristic granulomatous inflammation of the vessel wall commonly leads to local ischemia. Recent advances in immunological investigations have characterized the cellular components of the disease process, but the etiology has so far remained unresolved. A reappraisal of the clinical features of giant cell (temporal) arteritis demonstrates the heterogeneity of the manifestations of the disease, including ischemic optic neuropathy. A range of new laboratory investigations and blood flow studies with color Doppler imaging have demonstrated promising roles, with respect to diagnosis and long-term follow-up. Prompt diagnosis and expeditious treatment require a high index of clinical suspicion, particularly for atypical cases. Corticosteroids remain the treatment of choice, other immuno-suppressive agents being used as second line steroid-sparing agents. Giant cell (temporal) arteritis leads to increased vascular and visual morbidity and, if untreated, may prove fatal. To maintain high standards of management of this enigmatic disorder, ophthalmologists need to be aware of the clinical spectrum of giant cell (temporal) arteritis and currently available diagnostic tests and treatment strategies.

Laboratory investigations including liver in polymyalgia rheumatica/giant cell arteritis

The most useful investigation in supporting the clinical diagnosis of PMR/GCA is elevation of the ESR or viscosity. Acute phase proteins, particularly C-reactive protein, are also elevated but in most cases are not more helpful than the ESR in either diagnosis or follow-up. The definitive investigation is the demonstration of giant cell arteritis histologically, usually from temporal artery biopsy. The classical changes are internal elastic lamina fragmentation and destruction, with marked intimal thickening and an inflammatory infiltrate in the vessel wall with giant cells. Changes of healed arteritis can be distinguished from ageing changes and can therefore confirm the diagnosis. Positive biopsies are found in about 70% of patients with clinical GCA but are unlikely to be helpful in pure PMR. Elevation of alkaline phosphatase of liver origin is seen in one-third to half of patients with both PMR and GCA. Abnormal tracer uptake has been reported in radionuclide scans with a variety of non-specific abnormalities on liver biopsy. Promising developments include measurement of CD8+ lymphocytes and interleukins.

Immunological studies in giant cell arteritis

The results of investigations on the humoral immunological mechanisms are conflicting in giant cell arteritis (GCA) and have not been able to explain the pathological findings in the inflamed arterial wall. Altogether, immunological studies suggest that a cell-mediated immune reaction, possibly against an autologous antigen, occurs locally in the arteritic lesions of GCA. The excellent effect of treatment with glucocorticosteroids on the inflammation in GCA can also be explained by this model. The glucocorticosteroids inhibit the synthesis of interleukin-1 (IL-1) by the macrophages and suppress the IL-2 production from the T cells (Palacios, 1982). The observed HLA-DR expression in the arterial wall can be accounted for by the sum of macrophages and activated T cells, the macrophages being the most probable antigen-presenting cells. The interdigitating reticulum cells observed in some of the GCA patients may also be involved in antigen presentation. What the antigen(s) may be is, however, still unknown, as are the factors initiating the inflammatory process. It has recently been possible to extract T lymphocytes from the inflamed tissue and to culture these cells in vitro. After culture, it is possible to study the gene for the T-cell receptor, and probably even the antigenic specificity of the T cells. I hope that this approach may lead to a better understanding of the pathogenic mechanisms in GCA.

Temporal arteritis: cell composition and the possible pathogenetic role of cell-mediated immunity

A biopsy specimen exhibiting the typical morphologic characteristics of temporal arteritis was studied by using light immunofluorescent, and electron microscopy and immunohistochemical techniques. The granulomatous lesion consisted of clusters of macrophages, epithelioid cells, giant cells, and the peripheral lymphocyte mantle, and was localized mainly in the media. Neutrophils were rare, and fibrinoid necrosis was absent. In immunofluorescent and immunohistochemical studies, no significant deposition of immunoglobulins or complement was observed. Immunohistochemical study with monoclonal antibodies to leukocyte surface antigens demonstrated that the central aggregated granulomatous infiltrate consisted of OKTM1+, Leu-M3+, HLA-DR+ epithelioid macrophages and multinucleated giant cells, whereas OKT8+, HLA-DR+ (suppressor/cytotoxic) T cells predominated in the peripheral lymphocyte mantle. These findings suggest that cell-mediated immunity, especially T cell-regulated granulomatous reaction, may play an important role in the pathogenesis of temporal arteritis. By electron microscopy, smooth muscle cells often exhibited closely attached macrophages, epithelioid cells, and giant cells, and displayed a variety of cell injuries. It therefore seems likely that smooth muscle cells are a primary target of the granulomatous reaction.

T cell subsets and expression of immunological activation markers in the arterial walls of patients with giant cell arteritis

Immunohistochemical features of infiltrating mononuclear cells (MNC) and resident cells were studied in the temporal artery biopsy specimens of 13 patients with histological verified giant cell arteritis (GCA) and in six biopsy specimens from patients with GCA with negative histological findings. Eight temporal artery biopsy specimens from seven patients with unrelated diseases served as controls. In all patients with GCA proved by biopsy an infiltration of T lymphocytes in the arterial wall was observed, most being of the helper/inducer subset. No B lymphocytes, or very few, were seen. Lymphocytes in 10 out of the 13 positive biopsy specimens displayed staining for the class II major histocompatibility complex (MHC) antigen HLA-DR, whereas this was found in only two of eight controls. A minor number of the infiltrating T lymphocytes from seven out of 13 patients with GCA proved by biopsy stained for transferrin receptors, and in six out of the 13 cases they reacted with anti-interleukin 2 receptor antibody. In the arterial wall from all patients with histologically verified GCA we also found an increased number of macrophages, many of them expressing HLA-DR antigens and transferrin receptors. The immunohistochemical pattern of cell phenotypes found in the arterial wall of patients with GCA suggests that the infiltrating T cells are immunologically activated. This finding supports the hypothesis of a predominantly cellular immunological pathogenesis of giant cell arteritis.

Isolation and analysis of immune complexes from sera of patients with polymyalgia rheumatica and giant cell arteritis

Serum samples were obtained from patients with polymyalgia rheumatica (PMR: n = 10) or giant cell arteritis (GCA; n = 7), or both. Samples were taken either before treatment or within one week of starting prednisolone. Immune complexes (IC) were concentrated by polyethylene glycol (PEG) precipitation then purified with either IgG anti-C1q-Sepharose or IgG anti-C3c-Sepharose. Complex components were separated by sodium dodecyl sulphate (SDS) gradient polyacrylamide gel electrophoresis then transferred to nitrocellulose by Western blotting. Identification of proteins was carried out using specific antisera. All the IC contained IgM (mu chain), some contained IgA (alpha chain), and IgG (gamma chain). C1r, C1s, C1q, C3, C4, and C reactive protein (CRP), where tested, were found in most but not all IC. The occurrence of properdin, factor B, alpha 2 macroglobulin (alpha 2M), factor H (beta 1H), C1 esterase inhibitor, and C4 binding protein was also investigated. Immune complexes in PMR and GCA differed from those previously characterized in rheumatoid arthritis (RA)1 purified by anti-C1q-Sepharose which contained immunoglobulins and C1q only. No properdin or factor B were detected in RA IC purified with either anti-C1q-Sepharose or anti-C3c-Sepharose.

Temporal arteritis without an elevated erythrocyte sedimentation rate. Case report and review of the literature

An elevated erythrocyte sedimentation rate is regarded as a hallmark of temporal arteritis. Thirty-five cases of biopsy-proved temporal arteritis without an elevated erythrocyte sedimentation rate are identified, and a 36th case is described. All patients had age-adjusted normal Westergren sedimentation rates, 16 with sedimentation rates of 20 mm per hour or less and 20 with sedimentation rates of 21 to 40 mm per hour. Twenty-two patients had sufficient clinical information for analysis and comparison with reported series of patients with biopsy-proved temporal arteritis with an elevated Westergren sedimentation rate. Headache (41 percent), temporal artery abnormalities (41 percent), and visual symptoms (36 percent) were the most common manifestations in patients without an elevated sedimentation rate. Headache (41 percent versus 75 percent, p less than 0.05) and jaw claudication (9 percent versus 43 percent, p less than 0.025) were found less often in the patients without an elevated sedimentation rate. History and physical examination are essential in the diagnosis of temporal arteritis with a normal Westergren sedimentation rate.

Polymyalgia rheumatica and temporal arteritis

Polymyalgia rheumatica and temporal arteritis are a clinical syndrome and clinicopathologic entity, respectively. Polymyalgia rheumatica occurs more commonly than temporal arteritis, with approximately half of all patients with temporal arteritis having the polymyalgia rheumatica syndrome. Both conditions are found in the population over 50 years of age and are associated with an elevated ESR. The etiology of both is unclear, although genetic, and potentially, environmental factors may play significant roles. Both conditions respond to corticosteroid therapy, but patients with temporal arteritis require significantly higher doses to control symptoms and to prevent blindness.

Failure to detect immune complexes in the secondary stage of pityriasis rosea

Thirty-three patients with pityriasis rosea were studied with regard to the possible presence of circulating and cutaneously deposited immune complexes. The levels of circulating immune complexes, determined by a solid-phase C1q-binding assay, were not different from those of healthy control individuals. The levels were similar in samples obtained during the initial and during the remission stages of the disease. Cutaneous deposits of immunoglobulin and/or complement were found in only 5 of 33 patients. This study does not support of concept that circulating immune complexes are important for the development of the secondary skin lesions in pityriasis rosea.

Immunological changes in patients with previous malignant essential hypertension

Increased T-lymphocyte reactivity against human arterial antigen was significantly more common in a group of 20 patients with previously malignant essential hypertension than in matched control subjects. Serum-levels of IgG and IgM and the prevalence of autoantibodies were also significantly higher in the patients. It is suggested that these changes, whether primary or secondary, may contribute to or aggravate the vascular damage in this condition and are therefore of pathogenetic importance.