Intracranial non-Hodgkin lymphoma occurring after treatment of Hodgkin disease

Patients with successfully treated Hodgkin disease are at increased risk for the development of second malignancies. We present two cases of intracranial non-Hodgkin lymphoma that appeared following successful treatment of Hodgkin disease. The appearance of the lymphomas on computed tomographic images is shown, and possible predisposing factors, differential diagnosis, and clinical implications are discussed.     

Preliminary investigations on androgen receptor gene mutations in infertile men

A total of 50 men were selected from all patients attending an infertility clinic on the basis of oligozoospermia or azoospermia with concentrations of luteinizing hormone >6 IU/l and testosterone >30 nmol/l. Six of these men responded to written invitation and DNA was extracted from blood leukocytes. Individual exons of the androgen receptor gene were amplified by polymerase chain reaction and screened for the presence of mutations by denaturing gradient gel electrophoresis. The glutamine rich portion of exon 1 was sequenced directly. All of the coding sequence of the gene was examined except the glycine rich portion of exon 1 in all patients. No mutations or deletions were identified. Androgen receptor gene mutations do not appear to be present in infertile men with biochemical disturbances compatible with androgen resistance. It is therefore unlikely that such mutations are a major factor in the pathogenesis of oligozoospermia/azoospermia and infertility.      

New live mycobacterial vaccines: the Geneva consensus on essential steps towards clinical development

As the disease caused by Mycobacterium tuberculosis continues to be a burden, which the world continues to suffer, there is a concerted effort to find new vaccines to combat this problem. Of the various vaccines strategies, one viable option is the development of live mycobacterial vaccines. A meeting with researchers, regulatory bodies, vaccines developers and manufactures was held to consider the challenges and progress, which has been achieved with live mycobacterial vaccines (either modified BCG or attenuated M. tuberculosis). Discussion led to the production of a consensus document of the proposed entry criteria for Phase I clinical trials of candidate live mycobacterial vaccines. The vaccine must be characterised thoroughly to prove identity and consistency, as clinical trial lots are prepared. In pre-clinical studies, greater protective efficacy as well as improved safety potential relative to BCG should be considered when assessing potential vaccine candidates. A standard way to measure the protective efficacy to facilitate comparison between vaccine candidates was suggested. Additional safety criteria and verification of attenuation must be considered for attenuated M. tuberculosis. Two non-reverting independent mutations are recommended for such vaccines. When entering Phase I trials, enrollment should be based upon an acceptable characterisation of the study population regarding mycobacterium status and exclude HIV(+) individuals. BCG could be used as a comparator for blinding during the trials and to properly assess vaccine-specific adverse reactions, while assays are being developed to assess immunogenicity of vaccines. The proposed criteria suggested in this consensus document may facilitate the movement of the most promising vaccine candidates to the clinic and towards control of tuberculosis.     

The emergence of chemical genomics in drug discovery

The interaction of small organic molecules with proteins and other macromolecules is fundamental to drug action. Chemical genomics employs a combination of chemistry, genomics and informatics to study these drug-target interactions in a systematic and global manner in order to improve the efficiency of the drug discovery process.     

Positional cloning of a gene involved in hereditary multiple exostoses

Hereditary multiple exostosis (EXT) is an autosomal dominant condition mainly characterized by the presence of multiple exostoses on the long bones. These exostoses are benign cartilaginous tumors (enchondromata). Three different EXT loci on chromosomes 8q (EXT1), 11p (EXT2) and 19p (EXT3) have been reported, and recently the EXT1 gene was identified by positional cloning. To isolate the EXT2 gene, we constructed a contig of yeast artificial chromosomes (YAC) and P1 clones covering the complete EXT2 candidate region on chromosome 11p11-p12. One of the transcribed sequences isolated from this region corresponds to a novel gene with homology to the EXT1 gene, and harbours inactivating mutations in different patients with hereditary multiple exostoses. This indicates that this gene is the EXT2 gene. EXT2 has an open reading frame encoding 718 amino acids with an overall homology of 30.9% with EXT1, suggesting that a family of related genes might be responsible for the development of EXT.      

Inhibition of T cell proliferation by antibodies to synthetic peptides

While T cell proliferation to antigen in the presence of antigen-presenting cells is well known to be readily inhibited by antibodies directed against Class II major histocompatibility complex (MHC) (Ia/HLA-DR) products, it has not been possible to inhibit proliferation by antibodies directed against the antigen. Because of the implications of these observations for targets of T cell recognition, this phenomenon was reinvestigated using human T cell clones, recognizing a small (24 amino acid) synthetic peptide (termed p20) derived from the influenza hemagglutinin-1 molecule. It was found that proliferation of clones to p20 was inhibited efficiently (less than 90%), using p20 as antigen, and rabbit anti-p20. Inhibition was possible either by coculturing p20 antigen and antibody to p20 with cloned T cells and antigen-presenting (E-) cells, or by pulsing antigen-presenting cells with antigen prior to a brief incubation with antibody before washing the E- cells and using them to stimulate cloned T cells. These results do not indicate why previous attempts had failed, but in view of the different techniques available now (cloned T cells, small synthetic polypeptides, and antibody raised against polypeptide) we investigated the influence of these parameters. It was found that, using cloned T cells, the form of the antigen was of importance, as antibody inhibition of the response to hemagglutinin or whole influenza A was much less apparent. These differences were interpreted as being due to greater access of anti-p20 to p20 than to hemagglutinin or influenza. If uncloned T cell lines were used, inhibition was also much harder to detect. This was interpreted as masking of inhibition of the response of some clones in the line by interleukin 2-induced recruitment.     

Direct evaluation of antigen binding to human T lymphocyte clones: involvement of major histocompatibility complex products in antigen binding

Cloned human helper T lymphocytes reactive with a defined peptide (p20; residues 306-329) of the HA-1 molecule of influenza virus hemagglutinin were analyzed for their capacity to specifically bind peptide antigen. Three different methods of analyzing antigen binding to T cell receptors were compared. One method involved the binding of radiolabeled T cells to antigen-pulsed populations of sheep erythrocyte rosette-negative (E-) cells (B cells and monocytes). The binding was antigen specific, in that only E- cells pulsed with the appropriate antigen bound the treated T cells, and was inhibitable by free peptide. Furthermore, antigen binding was major histocompatibility complex-restricted in that only E- cells histocompatible at the HLA-D region locus bound the T cells, and monoclonal antibody of the relevant specificity was able to inhibit the binding. Secondly, it was demonstrated that tritiated T cells could bind to insolubilized antigen (p20) in the absence of E- cells. The binding was inhibited by anti-class II antibody suggesting that the interaction of antigen with the T cells involves recognition of T cell major histocompatibility complex class II determinants. Finally, radiolabeled peptides were also used to detect binding to the appropriate clones in the absence of presenting cells. This binding was specific, inhibitable by the appropriate unlabeled peptide and temperature dependent. These studies demonstrate that the process of antigen binding to receptors is analyzable and should in turn facilitate the analysis of the mechanism of T cell activation.