The trouble with T cells

Epidemiology of Classic Kaposi's Sarcoma, with Special Reference to Mediterranean Population

An excess of classic Kaposi's sarcoma (KS) in individuals of southern European ancestry has long been suspected and recently quantified in terms of age-standardized rates. In Italy and most notably in southern Italy for the period 1976-84, prior to the AIDS epidemic, KS incidence rates were two-to-three-fold higher than in the United States and Sweden and many ten-fold higher than in England and Wales and Australia. A high frequency of classic KS has also been documented in Israel and, in low-risk countries, in individuals born in southern Europe and the Middle East. Many infections have been suspected to play a role in the etiology of KS, including cytomegalovirus, malaria and, most recently, a new virus of the herpes family, identified in AIDS-associated and classic KS. The present review deals with epidemiologic data concerning KS in the Mediterranean and stresses the opportunity to combine the study of KS in AIDS as well as non-AIDS patients in order to shed light on this no longer rare disease.

Genotypic heterogeneity of node based peripheral T-cell lymphoma

PTCL represents a diverse group of histological entities that defy classification schemes based on normal T cell differentiation, differ in their clinical presentation and behave unpredictably. Genetic analyses of this phenotypically heterogeneous group have clearly shown that histologically defined PTCL may be subdivided on the basis of clonal gene rearrangements. The absence of clonal gene rearrangements in a significant proportion of PTCL cases has increased the complexity of classification. The data presented in this review suggest that a molecular classification would allow true reflection of PTCL aetiology, but carefully coordinated studies are required to evaluate the clinical usefulness of such a classification scheme.

T cell activation and T cell receptor variable region gene usage in measles

T cell activation and T cell receptor variable (V) regions were studied with monoclonal antibodies in peripheral blood lymphocytes from 22 patients with measles. Increased (greater than 5%) activated T cells (HLA-DR+ CD3+ cells) were noted in 14 of the 22 patients. Elevations of V beta 5+ and V beta 8+ T cells were observed in two and four patients, respectively, and appeared to be associated with T cell activation. The duration of fever was significantly prolonged in those with increased (greater than 10%) activated T cells (p less than 0.01). These results suggest that T cell activation and the preferential expansion of V beta 8+ and V beta 5+ T cells are associated with the pathogenic process of measles.

Hypotheses on the pathogenesis and natural history of Helicobacter pylori-induced inflammation

Although Helicobacter pylori is now recognized as playing an etiologic role in chronic gastritis and peptic ulcer disease, information on the pathogenesis and natural history of infection is limited. A model is proposed in which luminal H. pylori secrete substances that mediate inflammation that is beneficial to the organism but ultimately deleterious for the host; in addition to tissue damage, inflammation also affects gastric secretory function. In this model, the host may attempt to suppress the inflammatory response, and the adequacy of this postulated down-regulation determines pathological and clinical outcome. The effects of the inflammatory process on gastrin-hydrochloric acid homeostasis may be of critical importance in the pathogenesis of peptic ulcer disease. Because the long-term consequences of H. pylori colonization reflect the continued presence of the organism in the host over years or decades, it may be useful to consider this as a "slow" bacterial infection.

T lymphocyte activation in patients with active tuberculosis

Soluble interleukin-2 receptor (sIL-2R) is a marker of T lymphocyte activation. We measured the amount of serum sIL-2R in 35 patients with active tuberculosis before the initiation of antituberculous treatment. Twenty had pulmonary parenchymal lesion, 8 had tuberculous pleural effusion, and 7 had tuberculous lymphadenitis. The serum sIL-2R values were markedly elevated in patients with pulmonary tuberculosis (parenchymal lesion and pleural effusion) compared with patients with tuberculous lymphadenitis (2,612 +/- 536 versus 538 +/- 121 U/ml, p = 0.023), old, inactive tuberculosis (335 +/- 23 U/ml, p = 0.001), and normal control subjects (376 +/- 38 U/ml, p = 0.001). No significant difference was found between patients with parenchymal lesion and those with tuberculous pleural effusion. There was a positive correlation between serum sIL-2R values and the extent of disease on chest radiograph (r = 0.58, p less than 0.001). We conclude that the amount of sIL-2R may be a useful marker of disease activity and extent of involvement in patients with active tuberculous lesions.