The influence of antigen digestion on orally induced immunity and tolerance.

1. Pepsin-digested form of OVA has approximately the same molecular weight as native OVA, but differs in charge and isoelectric focusing point. 2. Pepsin-treated OVA retains most of the native OVA T- and B-cell determinants. 3. Delayed-type hypersensitivity response is suppressed when pepsin-treated OVA is administered i.p. to naive mice. 4. Cimetidine treatment of mice prior to ingestion of OVA shows decreased tolerance, while oral administration of pepsin-treated OVA to cimetidine-treated mice leads to a complete immune unresponsiveness; this suggests an important role for gastric digestion in orally induced immune tolerance.

Characterization of aerosols from biomass burning--a case study from Mizoram (Northeast), India.

Physical and optical properties of biomass burning aerosols in Northeastern region, India analyzed based on measurements made during February 2002. Large spatial extent of Northeastern Region moist tropical to moist sub-tropical forests in India have high frequency of burning in annual dry seasons. Characterization of resultant trace gases and aerosols from biomass burning is important for the atmospheric radiative process. Aerosol optical depth (AOD) observed to be high during burning period compared to pre- and post-burning days. Peak period of biomass burning is highly correlated with measured AOD and total columnar water vapor. Size distribution of aerosols showed bimodal size distribution during burning day and unimodal size distribution during pre- and post-burning days. Size distribution retrievals from biomass burning aerosols show dominance of accumulation mode particles. Weighted mean radius is high (0.22 microm) during burning period. Columnar content of aerosols observed to be high during burning period in addition to the drastic reduction of visibility. During the burning day Anderson sampler measurements showed dominance of accumulation mode particles. The diurnal averaged values of surface shortwave aerosol radiative forcing af biomass burning aerosols varies from -59 to -87 Wm(-2) on different days. Measured and modeled solar irradiances are also discussed in the paper.

Depolarization ratio measurement using single photomultiplier tube in micropulse lidar.

The conventional dual polarization micropulse lidar uses two separate photomultiplier tubes (PMT) to detect both the copolarized and cross-polarized beam. The prominent sources of error in the depolarization ratio measurement are mismatch in PMT, improper selection of discriminator threshold and unequal PMT high voltage. In the present work a technique for the measurement of lidar depolarization ratio using only one PMT sensor has been developed. The same PMT detects both copolarized and cross-polarized lidar backscatter. A stepper motor is used along with the mirrors to bring both the received polarization signals over the PMT window. Application of the same PMT minimizes the error caused in the depolarization ratio measurement due to error in photon counting of an individual channel. The design description of this technique along with the preliminary results depicting its functionality has been mentioned in this article.

Stratospheric trace constituent profile retrievals using laser heterodyne radiometer IR limb sensing spectra.

A retrieval technique for use with high resolution IR solar occultation limb sensing data is described for profiling stratospheric trace constituents. Remote measurement of CIO during sunset in the 24-45-km region with a 2-km height resolution is chosen as an example. Two types of instruments are considered: a laser heterodyne radiometer with line resolving spectral resolution and an interferometer spectrometer with a fixed slit width of 0.02 cm(-1). It is pointed out that a multichannel approach is necessary with the heterodyne instrument for improved retrieval accuracy. The error analysis indicates the relative sizes of instrument noise and other sources of error in the retrieval of altitude profiles with high (2-km) vertical resolution.

Effect of in vivo depletion of CD4+ and CD8+ cells on the induction and maintenance of oral tolerance.

The role of CD8+ and CD4+ cells in the generation and maintenance of high-dose oral tolerance has been investigated. Mice depleted of CD8+ cells prior to or subsequent to oral tolerization with OVA continued to express suppressed humoral and/or T cell proliferative responses to the homologous antigen. To assess the effect of CD4+ cell depletion on oral tolerance, mice were depleted of CD4+ cells prior to or subsequent to oral tolerization with OVA. After 50% regeneration of CD4+ cells was achieved, OVA-immunized mice produced anti-OVA immune responses that were comparable to those of water-fed control mice. Thus, under our experimental conditions the presence of CD4+ but not CD8+ cells is required to both establish and maintain oral tolerance.

Activation patterns of murine T cells after oral administration of an enterocoated soluble antigen.

An orally administered soluble protein antigen, ovalbumin (OVA), enterocoated with an acid-resistant acrylic polymer, induced a strong humoral immune response in BDF1 mice, exhibiting Th2 cell phenotype, typified by increased OVA-specific IgA, IgG1, and IgE antibody responses. This antibody response was accompanied by OVA-specific T cell proliferation response and IL-4 cytokine production. Mice fed enterocoated OVA and administered anti-IL-4 mAb showed a shift of the immune response toward the Th1 cell phenotype as evidenced by increased IFN-gamma production and anti-OVA IgG2a isotype antibody response. Additionally, in mice fed OVA solution and simultaneously administered anti-IL-4, we saw a slight but significant expression of Th1 cell phenotype. In conclusion, our data indicate that the dominance of Th2 cell phenotype in oral immunity is strongly influenced by the production and presence of IL-4.

Activation patterns of murine B cells after oral administration of an encapsulated soluble antigen.

Oral administration of soluble protein antigen, ovalbumin (OVA), encapsulated by an acid-resistant acrylic polymer, induced a strong immune response in BDF1 mice. Mice fed the encapsulated OVA showed activation of antigen-specific IgA, IgG and IgG1 isotype antibody-secreting cells which migrated to various lymphoid tissues via the common mucosal immune system traffic pathway. The highest number of antigen-specific antibody secreting cells was found in the Peyer's patches isolated from the upper segment of the small intestine, with their numbers declining along the length of the intestinal tract. Oral administration of this product suggests activation of lymphocytes exhibiting Th2 phenotype as shown by OVA-specific IgA and IgG1 isotype antibody responses. In conclusion, we demonstrated that oral administration of encapsulated soluble protein, in the absence of adjuvant, can activate the murine common mucosal immune system.

Coexistence of red cell aplasia and autoimmune haemolytic anaemia in a family.

Red cell aplasia is thought to have an immunological basis and has been reported to exist in association with various immunological abnormalities including autoimmune haemolytic anaemia in the same patient. A case is reported of a patient with pure red cell aplasia probably of acquired primary variety; but laboratory tests revealed only slight immunological abnormalities. On the other hand, the mother of the patient had autoimmune haemolytic anaemia. It is believed that such a familial coexistence of the diseases may further support the immunological basis of red cell aplasia.

Activation patterns of murine B cells after oral administration of an encapsulated soluble antigen.

Oral administration of soluble protein antigen, ovalbumin (OVA), encapsulated by an acid-resistant acrylic polymer, induced a strong immune response in BDF1 mice. Mice fed the encapsulated OVA showed activation of antigen-specific IgA, IgG and IgG1 isotype antibody-secreting cells which migrated to various lymphoid tissues via the common mucosal immune system traffic pathway. The highest number of antigen-specific antibody secreting cells was found in the Peyer's patches isolated from the upper segment of the small intestine, with their numbers declining along the length of the intestinal tract. Oral administration of this product suggests activation of lymphocytes exhibiting Th2 phenotype as shown by OVA-specific IgA and IgG1 isotype antibody responses. In conclusion, we demonstrated that oral administration of encapsulated soluble protein, in the absence of adjuvant, can activate the murine common mucosal immune system.