Requirements for the development of IL-4-producing T cells during intestinal nematode infections: what it takes to make a Th2 cell in vivo

Summary: Components of the type 2 immune response may mediate host protection against both helminthic parasites and harmful allergic responses. A central player in this response is the T‐helper 2 (Th2) effector cell, which produces interleukin (IL)‐4, IL‐5, IL‐13, and other Th2 cytokines during the primary and memory response. Specific aspects of the parasite that trigger Th2‐cell differentiation are not yet defined. Furthermore, the cell types and cell surface and secreted molecules that provide the immune milieu required for the development of Th2 effector cells and also Th2 memory cells are not well understood. They will probably vary with the particular helminth or other antigen inducing the Th2 response. We have used third stage larvae of intestinal nematode parasites as adjuvants to promote naïve nonparasite antigen‐specific T cells to differentiate into Th2 cells. This model system avoids possible parasite antigen‐specific T‐cell clones or cross‐reactive memory T cells that may preferentially differentiate into Th2 effector cells during the course of infection and confound the stereotypical components of parasite‐induced Th2 cell differentiation. We have found that these parasites have a potent adjuvant effect and have used our model system to begin to investigate the events that lead to the development of polarized Th2 cells in vivo.     

An in vitro and in vivo study of the effect of incorporation of chlorhexidine into autopolymerizing acrylic resin plates upon the growth of Candida albicans

Chlorhexidine acetate was incorporated into autopolymerizing acrylic resin and, after studying its ability to diffuse out in vitro, an investigation was made into the potential of the mixture to treat palatal candidosis in the rat. Chlorhexidine was found to diffuse out of acrylic in fungicidal concentrations for up to three weeks when mixed with the acrylic powder in the proportion of 7.5% (w/w). At this concentration it was found that palatal candidosis as produced by the technique of Shakir et al. was cured or prevented. However, rats fitted with chlorhexidine supplemented plates were found not to take sufficient food during the experimental period to maintain their body weight.     

Analysis and gene assignment of mRNAs of a paramyxovirus, simian virus 5

Polypeptides synthesized by the paramyxovirus SV5 in infected CV-1 cells were readily identified when the host cell was treated with actinomycin D. The unglycosylated forms of HN and Fo synthesized in infected cells in the presence of tunicamycin and HN and Fo synthesized in vitro were identified by immunoprecipitation with specific antibodies. Separation of SV5-specific poly(A)-containing RNAs on methyl-mercury agarose gels and in vitro translation of fractions, indicated that the viral polypeptides were translated from individual mRNAs except P (Mr approximately 44K) and the nonstructural polypeptide V (Mr approximately 24K) for which the mRNAs could not be separated. cDNA copies of SV5-specific mRNAs were synthesized and cloned in plasmid pBR322. Clones to NP, P + V, M, F, and HN were identified by hybrid-arrest and hybrid-selection translation of SV5 mRNAs. Tryptic peptide mapping of polypeptides P and V indicated that the peptides of V were a subset of those of P. Hybridization of cDNA probes to infected cell mRNAs separated on agarose gels permitted identification of the NP, P + V, M, F, and HN mRNAs and presumptive polycistronic mRNAs. The sizes and sequence homologies of these polycistronic mRNAs were used to derive a likely gene order on the SV5 50 S genome RNA.     

Inositol lipid metabolism in human T lymphocytes activated via the T3 complex.

Cloned human T lymphocytes and a mitogenic monoclonal antibody (UCHT1) that binds to the T3 antigen complex were used to study the role of inositol lipid hydrolysis in T-cell activation. Binding of the T3 molecular complex with anti-T3 antibody induced the generation of inositol trisphosphate after a lag of 1 min. While this is commensurate with the rise in cytosolic Ca2+ in these cells, examination of the inositol lipid revealed that phosphorylation of phosphatidylinositol 4-phosphate to phosphatidylinositol 4,5-bisphosphate occurred before the generation of inositol trisphosphate. Thus, activation of an inositol lipid kinase appears to be one of the primary signals in cellular activation in human T lymphocytes.     

Mutations of the GREAT gene cause cryptorchidism

In humans, failure of testicular descent (cryptorchidism) is one of the most frequent congenital malformations, affecting 1-3% of newborn boys. The clinical consequences of this abnormality are infertility in adulthood and a significantly increased risk of testicular malignancy. Recently, we described a mouse transgene insertional mutation, crsp, causing high intraabdominal cryptorchidism in homozygous males. A candidate gene Great (G-protein-coupled receptor affecting testis descent), was identified within the transgene integration site. Great encodes a seven-transmembrane receptor with a close similarity to the glycoprotein hormone receptors. The Great gene is highly expressed in the gubernaculum, the ligament that controls testicular movement during development, and therefore may be responsible for mediating hormonal signals that affect testicular descent. Here we show that genetic targeting of the Great gene in mice causes infertile bilateral intraabdominal cryptorchidism. The mutant gubernaculae fail to differentiate, indicating that the Great gene controls their development. Mutation screening of the human GREAT gene was performed using DHPLC analysis of the genomic DNA from 60 cryptorchid patients. Nucleotide variations in GREAT cDNA were found in both the patient and the control populations. A unique missense mutation (T222P) in the ectodomain of the GREAT receptor was identified in one of the patients. This mutant receptor fails to respond to ligand stimulation, implicating the GREAT gene in the etiology in some cases of cryptorchidism in humans.     

Immersion fixation methods for glycol methacrylate-embedded testes

Routine processing of testicular tissue through 10% neutral buffered formalin (NBF) into paraffin produces severe cellular shrinkage which obscures most of the morphologic detail. The following studies were performed to compare different combinations of immersion fixatives and embedding media for optimal cellular detail in the final histologic sections. We examined sections of testes from rats, mice, and rabbits fixed in either NBF, Bouin's, Zenker's, or Helly's fixatives, and embedded in either standard paraffin or glycol methacrylate. The results were similar in all 3 species. In paraffin, Bouin's or Helly's fixatives produced the fewest artifacts, while in glycol methacrylate, NBF-fixed tissue showed the greatest intracellular detail and preservation. The merits and limitations of each method are discussed for the rat, with exceptions for the other species noted where appropriate. The use of glycol methacrylate as the support medium for sectioning makes high-quality tissue sections available from formalin-fixed testes.     

Breast cancer risk associated with ovulation-stimulating drugs

BACKGROUND: Despite the recognized role of hormones in the aetiology of breast cancer, there has been little evaluation of hormonal preparations used to treat infertility. METHODS: A retrospective cohort study of 12,193 women evaluated for infertility between 1965 and 1988 at five clinical sites identified 292 in situ and invasive breast cancers in follow-up through 1999. Standardized incidence ratios (SIRs) compared breast cancer risks with those of the general population. Analyses within the cohort estimated rate ratios (RRs) associated with medications after adjustment for other breast cancer predictors. RESULTS: Infertile patients had a significantly higher breast cancer risk than the general population [SIR = 1.29, 95% confidence interval (CI) 1.1-1.4]. Analyses within the cohort showed adjusted RRs of 1.02 for clomiphene citrate and 1.07 for gonadotrophins, and no substantial relationships to dosage or cycles of use. Slight and non-significant elevations in risk were seen for both drugs after > or = 20 years of follow-up (RRs = 1.39 for clomiphene and 1.54 for gonadotrophins). However, the risk associated with clomiphene for invasive breast cancers was statistically significant (RR = 1.60, 95% CI 1.0-2.5). CONCLUSIONS: Although there was no overall increase in breast cancer risk associated with use of ovulation-stimulating drugs, long-term effects should continue to be monitored.     

Effects of platelet-derived growth factor and epidermal growth factor on antigen-induced proliferation of human T-cell lines.

When the serum content of tissue culture medium is reduced from 10% to 1%, the capacity of T cells to proliferate in response to antigen within that medium is dramatically reduced. Physiological concentrations of platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) are able to partially replace the requirement for serum, in that they are able to increase antigen-driven T-cell proliferation at a serum concentration of 1%. Neither growth factor is mitogenic for T cells in the absence of antigen, and neither is able to act synergistically with T-cell growth factor (TCGF) or IL-2) in the absence of antigen. Antigen-presenting cells (APC) pulsed with antigen in the presence of PDGF or EGF are able to stimulate antigen-specific T-cell proliferation to a greater extent than antigen-presenting cells pulsed in the absence of exogenous PDGF or EGF. Both growth factors increase the expression of MHC Class II antigens on antigen-presenting cells.