Investigation of the association of major histocompatibility complex genes, including HLA class I, class II and TAP genes, with clinical forms of Crohn's disease.

The aim of this study was to determine immunogenetic markers of susceptibility in Crohn's disease (CD), taking the different features of the clinical course of the disease into account. HLA class I, HLA class II and TAP transporter gene polymorphisms were studied using DNA typing methods. Gene and antigen frequencies were analysed and compared in a group of 102 CD patients and 200 unrelated healthy controls from the same area. Analysis of the whole CD patient population revealed no definite association with either HLA or TAP gene alleles, with the exception of an association with DRB1*1302 (Pc < 0.05). However, when clinical subgroups of patients were considered, specific associations with some genetic markers were found. The most definitive results involved a genetic association in the group of patients who did not respond to glucocorticoid therapy. This group was characterized by a high frequency of HLA-DRB1*04 (P < 0.05). Conversely, a positive association with the TAP2-A allele was found in cortico-responder patients (Pc < 0.03). Furthermore, analysis of the distribution of HLA class II alleles in relation to the presence of extra-intestinal manifestations revealed an association with the DQB1*0501 or *0503 suballele of DQ5 (P < 0.05). Finally, patients with lesions in the small bowel were more frequently HLA DRB1*07 (P < 0.05). The present study supports the concept of clinical heterogeneity in Crohn's disease associated with a background of genetic heterogeneity.

Pulmonary toxoplasmosis in HIV-infected patients: usefulness of polymerase chain reaction and cell culture.

Toxoplasmosis is a serious opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). The lung is a major site of infection after the central nervous system. The aim of the study was to assess the polymerase chain reaction (PCR) and cell culture for the detection of Toxoplasma gondii. One hundred and thirty two human immunodeficiency virus (HIV)-infected patients with respiratory manifestations, who underwent fibreoptic bronchoalveolar lavage, were investigated. Detection of Toxoplasma gondii was compared using three techniques: Giemsa staining; polymerase chain reaction with specific primers derived from the P30 gene; and culture on the MRC5 cell line. Toxoplasma gondii was detected in the same four samples by all three techniques. We conclude that PCR adds little to conventional (and cheaper) tools already used to diagnose pulmonary toxoplasmosis.