Natural killer T cells and the regulation of asthma.

A crucial role has been suggested for invariant natural killer T cells (iNKT) in regulating the development of asthma, a complex and heterogeneous disease characterized by airway inflammation and airway hyperreactivity (AHR). iNKT cells constitute a unique subset of T cells responding to endogenous and exogenous lipid antigens, rapidly secreting a large amount of cytokines, which amplify both innate and adaptive immunity. Herein, we review recent studies showing a requirement for iNKT cells in various models of asthma in mice and monkeys as well as studies in human patients. Surprisingly, in several different murine models of asthma, distinct subsets of iNKT cells were required, suggesting that iNKT cells serve as a common critical pathogenic element for many different forms of asthma. The importance of iNKT cells in both allergic and non-allergic forms of asthma, which are independent of adaptive immunity and associated with airway neutrophils, may explain situations previously found to be incompatible with the Th2 paradigm of asthma.

Detection of herpes simplex virus type 2 Bgl II N fragment in paraffin-embedded cervical tissue sections using nested polymerase chain reaction.

To study the presence of transforming sequence Bgl II N of HSV-2 in cervical cancer tissues, we developed the nested polymerase chain reaction (PCR) for detecting such a sequence in paraffin-embedded cervical tissue sections. Samples derived from 46 patients with premalignant and malignant lesions were tested. The sequence was found in 20-25% of total cases tested but not observed in any of the normal healthy controls. This study also indicates that for the detection of HSV-2 Bgl II N sequence in cervical tissue, the nested PCR may be more reliable than the in situ hybridization method.

Preparation, characterization and immunogenicity of various polymers and conjugates of elapid postsynaptic neurotoxins.

Seven polymeric forms and conjugates of purified principal postsynaptic neurotoxins of Naja naja siamensis (NNS), Ophiophagus hannah (OH) and Bangarus fasciatus (BF) have been synthesized by controlled polymerization in which only 29-60% of the toxins were allowed to react. A carbodiimide (ECDI) and glutaraldehyde (GA) were used as coupling agents while BSA and tetanus toxoid (TT) were used as carriers. The antigenic mosaic of these immunogens was: NNS-ECDI, NNS-BF-OH-ECDI, NNS-BSA-ECDI, NNS-TT-ECDI, NNS-BF-OH-TT-ECDI, NNS-GA and NNS-BF-OH-GA. By using SDS-PAGE and radioactive toxin, each immunogen preparation was characterized in terms of molecular size and abundance of protein components, percent toxin reacted and toxin density. The relative immunogenicities of the immunogens along with those of NNS venom and pure NNS neurotoxin were evaluated in groups of eight rats. The levels of specific antibody against each of the neurotoxins were determined by ELISAs. Multiple comparisons between antibody responses to these immunogens were made. All the chemically modified immunogens were at least as immunogenic as NNS venom. NNS-TT-ECDI gave the highest antibody response (2.7-6.2-fold higher than that induced by NNS venom). All three multispecific immunogens induced comparable specific antibodies to BF, OH and NNS neurotoxins. The results showed that the presence of TT carrier and the relative degree of toxin density affected the immunogenicities. Some of the immunogens reported here should be useful for the production of potent, polyvalent antivenoms against elapid snakes.

Intratypic variations in neutralizable epitopes among herpes simplex virus type 2 isolates.

Intratypic variation among 94 isolates of herpes simplex virus type 2 (HSV-2) was investigated using 4 different monoclonal antibodies (MAbs). By neutralization test, these MAbs appeared to be directed to at least 2 distinct epitopes on the viral glycoprotein D (gD), i.e., 6G6.G9 and 6E8.F11 which did not require complement (C-MAb) and gD-105 and gD-110 whose neutralizing activities could be enhanced by complement (C+MAb). The C-MAb pairs each separately could detect significant intratypic variations among the isolates. Whether these variations also existed in the gD epitope(s) recognized by C+MAbs remains to be elucidated. The results suggested that intratypic variation occurred on at least one of the neutralizable (thus related to protective immunity) epitopes on gD of HSV-2.

Epidemiological study of enteric coronavirus excretion by an enzyme-linked immunosorbent assay.

The enzyme-linked immunosorbent assay with a blocking test was used to determine the prevalence of enteric coronavirus excretion among the population of Bangkok and Khon Kaen province. The results indicated that coronaviruses were present in fecal samples from both children and adults with or without diarrhea. It is interesting that the viruses were more frequently observed in the apparently healthy individuals in Bangkok than in the patients with diarrhea whereas the excretion rates were approximately alike in both groups in Khon Kaen province. Among children aged less than 5 years (with or without diarrhea) the viruses were more frequently observed in stools from young children (1-5 years old) than from the newborn (less than 1-year-old) particularly those living in the Bang Khen slum area and in the rural Khon Kaen community. The rate of coronavirus excretion did not increase with age and some apparently healthy individuals continued to excrete the viruses for several months. The results also suggested that chronic parasitic infection associated with low socioeconomic status might influence the excretion of enteric coronaviruses in the feces.

Antigenic relationships and relative immunogenicities of venom proteins from six poisonous snakes of Thailand.

Venoms from Naja naja siamensis, Ophiophagus hannah, Bungarus fasciatus, Vipera russelli, Calloselasma rhodostoma and Trimeresurus albolabris have been studied by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. The immunoblots were stained with rabbit homologous and heterologous antibodies. In general, the higher the mol. wt the protein the higher the immunogenicity although two proteins with mol. wts of 23,000 and 25,000 from O. hannah venom are extraordinarily immunogenic. Cross reacting and species specific venom proteins were readily identified by the immunoblot techniques. Only a small number of venom proteins were cross-reactive among the snake species tested while the remaining appeared to be species specific.

Immunodiagnosis of snake venom poisoning.

Uncertainty as to the species diagnosis remains a serious problem in the management of snake venom poisoning. This is particularly so in areas inhabited by numerous species, the venoms of which elicit similar pharmacological effects and clinical symptoms and against which para-specific cross-neutralizing antivenom is not available. Attempts have been made to eliminate some of this ambiguity through the development of various immunodiagnostic tests. Tests based on ELISA are sensitive, specific and even quantitative and adaptable to field application. In the development of diagnostic tests for use in developing countries, however, practical consideration must be given to speed, cost, simplicity in terms of equipment and expertise, and stability to the climate and storage conditions. This may dictate further modification or selection of more suitable alternative methodologies. Furthermore, the test may have to allow more flexibility in accommodating local species distributions and to address probable complications of heterophile antibodies in test samples from rural people.

T-cell subpopulations in tuberculosis and the effects of rifampicin.

T-cell subpopulations were evaluated by several recent methods in 38 tuberculosis patients (24 active and 10 quiescent cases of pulmonary tuberculosis; two of miliary and two of active extra-pulmonary tuberculosis) before and during rifampicin (RMP) treatment. There was a significant reduction in the total number of T cells (E-RFC and OKT3+ cells) and of helper T cells (OKT4+) coinciding with an increase in the number of suppressor T cells when the 38 tuberculosis patients were compared with 21 healthy control subjects. When the changes of T-cell subpopulations in groups of subjects and patients with different clinical forms of the disease were analysed, these changes could be clearly shown with both sets of assays (receptor assays and monoclonal antibody assays) among those with the active pulmonary form of tuberculosis while similar changes could be demonstrated only by one or the other assay among those with the other forms of the disease. The effects of one month of RMP treatment on these parameters were much more obvious among the clinically active patients than the quiescent patients, i.e. a recovery of total T cells from a low pre-treatment to a near normal level accompanied by a significant reduction in the number of suppressor cells (OKT8+). In fact, among quiescent patients the number of suppressor cells (as TG) appeared to rise further with RMP treatment.

Antibody reactivity against trophoblast and trophoblast products.

Sensitive immunoassays have been applied to WHO reference bank sera from fertile and infertile women in order to assess any naturally occurring antibody reactive with isolated human placental trophoblast membranes or two separate trophoblast protein products (hCG and SP1). A very low incidence of antibody reactive with solubilised trophoblast membrane was detected, and no significant antibody to either hCG or SP1 could be detected. Infertile states represented within this serum bank appear unlikely to involve adverse immune reactions to trophoblast.

New approaches to immunological contraception.

PIP: Focus is on the various approaches to immunological contraception, the obstacles encountered, progress made thus far, and possible strategy for future studies. Attention is directed to: immunoregulation in materno-fetal interactions (modulation of the immune response, immunological unresponsiveness); development of a contraceptive vaccine (potential complications, guidelines for safety, potential antigens, ovum-specific antigens, placenta-specific antigens, hormonal antigens; other hormonal approaches); and immunological approaches unrelated to vaccine. There are substances which are unique to the reproductive system, and active or passive immunization of experimental animals with some of these substances has led to antifertility effects. Despite these encouraging results, efforts to develop a contraceptive vaccine have met with several problems. A high degree of antifertility efficacy is required, and this has proved difficult to achieve. Several potential candidate antigens have had to be dropped due to poor immunogenicity. Other substances with reasonable immunogenicity in heterologous models may prove to be poorly immunogenic in homologous immunization. Potential immunological hazards of immunization with material derived from human sources necessitate the use of extreme caution in the development of a contraceptive vaccine. Despite obstacles, there has been progress. The problem of potential immunological hazards has been circumvented by selected truly unique substances of the gametes or early conceptus and encouraging results have been obtained with LDH-X (sperm enzyme) and human chorionic gonadotropin.^ieng