Antibodies specific for VB8 receptor peptide suppress experimental autoimmune encephalomyelitis.

Recent studies from our laboratory have shown, for the first time, that a synthetic peptide from that TCR VB chain used preferentially by encephalitogenic T cells induced the formation of protective, MHC class I-restricted T cells and prevented the development of EAE in Lewis rats. In this report we 1) demonstrate that immunization with the TCR-VB8-39-59 peptide generated peptide-specific antibodies that protect against experimental autoimmune encephalomyelitis induced by either of the two distinct encephalitogenic epitopes of basic protein, and 2) characterize the production and biologic functions of rat and rabbit antibody responses to the TCR peptide. The antibodies in both species increased in titer over time, were highly specific for the immunogen by direct reaction and inhibition assays, stained only VB8+ T cells, and suppressed clinical signs and to lesser extent the number of histologic lesions of experimental autoimmune encephalomyelitis mediated by VB8+ T cells. Coupled with our previous work, these results indicate that both humoral and cellular responses to the TCR-VB8-39-59 peptide can contribute independent immunoregulatory effects on encephalitogenic T lymphocytes that use common V region genes in response to epitopes of myelin basic protein.     

Purification, crystallization, and X-ray diffraction studies of lactotransferrin from buffalo colostrum.

Lactotransferrin is an iron-binding protein. It has been purified from buffalo colostrum. The purified lactotransferrin has been crystallized in 10% ethanol solution. The crystals are orthorhombic and the space group is P2(1)2(1)2(1) with unit cell dimensions a = 161.70 A, b = 155.75 A, c = 113.48 A. The asymmetric unit contains three molecules of the protein with a solvent content of about 59%. The crystals were stable in the X-ray beam and diffract beyond 3.5 A resolution. The native data have been collected and the structure determination is in progress.     

cDNA sequence of the small subunit of the hamster ribonucleotide reductase.

Ribonucleotide reductase activity is markedly elevated in cell lines selected for resistance to hydroxyurea, a cytotoxic drug known specifically to inhibit ribonucleotide reductase. From a cDNA library constructed from a highly hydroxyurea-resistant hamster lung cell line, 600H in which the activity is elevated more than 80-fold, we have isolated a full length cDNA for the small subunit of the reductase. The cDNA is 3.48 kb long with an open reading frame of 1158 nucleotides and a long 3' flanking region of 2169 nucleotides from the termination codon. The derived polypeptide sequence is closely similar to the small subunit of the mouse, differing from it in 20 amino acid positions. Most of these replacements occur in the N-terminal segment of the protein. The hamster subunit does not contain 4 amino acid residues found in the mouse small subunit near the C-terminal end. RNA blots probed with the cDNA show two poly(A)+ RNA species which are elevated in hydroxyurea-resistant cells.     

Role of Ca2+ in induction and secretion of dengue virus-induced cytokines

The present study was undertaken to investigate the role of calcium ions (Ca₂₊) in the induction and secretion of the dengue type 2 virus induced cytotoxic factor and the cytotoxin. This was done by using calcium channel blocking drugs such as verapamil, nifedipine or diltiazem hydrochloride. The production of cytotoxic factor was significantly reduced by treatment of dengue type 2 virus infected mice with verapamil. Similarly, a dosedependent inhibition of the secretion of cytotoxic factor was observed, when spleen cells of the virus-primed mice were treatedin vitro with the 3 calcium channel blockers. The production of cytotoxin by macrophages was abrogated by pretreatment with calcium channel blockers but had little effect on its secretion as shown by treatment of macrophages with verapamil at 1 h after the induction to later periods up to 18 h. The findings thus show that in the induction of both the cytokines Ca₂₊ plays a critical role; on the other hand it is required for the secretion of the cytotoxic factor but not for that of the cytotoxin.     

Pattern recognition in honeybees: chromatic properties of orientation analysis

The spectral properties of the discrimination of pattern orientation in freely flying honeybees (Apis mellifera) were examined. Bees were trained to discriminate between two random black/white gratings oriented perpendicularly to each other, one of which was associated with a reward. Subsequently the bees were tested on two-colour gratings or gratings consisting of grey and coloured stripes, providing a range of different chromatic contrasts, luminance contrasts and specific channel contrasts. The results of these experiments indicate that orientation analysis in the honeybee is mediated almost exclusively by the green receptor channel, although the bee's visual system as a whole is endowed with excellent trichromatic colour vision.