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Olfaction influences many insect behaviours including mate seeking and host selection. The molecular machinery underlying insect olfactory systems is a G protein-coupled receptor pathway that, in addition to activation, requires adaptation for olfactory sensitivity and discrimination. We have previously identified ARR1 (henceforth AgARR1), a sensory arrestin from the malaria vector mosquito Anopheles gambiae that has been postulated to modulate olfactory adaptation. This report describes three additional arrestin family members including ARR2 (henceforth AgARR2), which is similar to previously characterized insect sensory arrestins and is expressed at significantly higher levels in the antennae of male vs. female A. gambiae mosquitoes. This finding is consistent with the hypothesis that AgARR2 may be important for the regulation of olfactory-driven behaviours particular to male mosquitoes.

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Arrestins are important components for desensitization of G protein-coupled receptor cascades that mediate neurotransmission as well as olfactory and visual sensory reception. We have isolated AgArr1, an arrestin-encoding cDNA from the malaria vector mosquito, Anopheles gambiae, where olfaction is critical for vectorial capacity. Analysis of AgArr1 expression revealed an overlap between chemosensory and photoreceptor neurons. Furthermore, an examination of previously identified arrestins from Drosophila melanogaster exposed similar bimodal expression, and Drosophila arrestin mutants demonstrate impaired electrophysiological responses to olfactory stimuli. Thus, we show that arrestins in Drosophila are required for normal olfactory physiology in addition to their previously described role in visual signaling. These findings suggest that individual arrestins function in both olfactory and visual pathways in Dipteran insects; these genes may prove useful in the design of control strategies that target olfactory-dependent behaviors of insect disease vectors.

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Antibodies to human myeloperoxidase and cathepsin G have been detected in the serum of some patients with systemic lupus erythematosus. Therefore, the presence of antibodies to human myeloperoxidase and cathepsin G was examined in glomerular immune deposits. Glomerular basement membrane fragments were prepared from renal tissues obtained at autopsy from 19 patients with systemic lupus erythematosus. IgG was extracted from the glomerular basement membrane fragments and tested with sensitive immunoassays for antibodies to myeloperoxidase and cathepsin G. Antibodies to cathepsin G were not detected in the extracts but antibodies to human myeloperoxidase were found in extracts of one specimen. In the extract with 6M guanidine hydrochloride these antibodies were enriched 103-fold, compared to the initial supernatant of glomeruli, which served as a serum surrogate. The recovered antibodies to myeloperoxidase accounted for 12% of the recovered IgG. These findings add autoantibodies to human myeloperoxidase to the list of antibodies that have been shown to be present in glomerular immune deposits of patients with lupus glomerulonephritis.

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Previous studies conclude that the repertoire of B-1a (CD5+ B) cells is highly restricted. Studies here, which use FACS sorting and single-cell PCR methodology to develop an unbiased representation of the IgH repertoires of B-1a, B-1b, and conventional B cells from the peritoneal cavity, demonstrate that the B-1a cell repertoire is more diverse than previously thought. Furthermore, adult B-1a cells have significantly fewer noncoded nucleotide (N) insertions than conventional B cells. However, B-1a cells are not defined by the absence of these regions, since such insertions are present in two-thirds of B-1a cell transcripts. All three B cell populations use a wide spectrum of V(H), D, and J(H) elements and display considerable diversity in complementarity-determining region 3 (CDR3). However, characteristic differences in the repertoires of all three B cell populations also exist, suggesting different selective and/or developmental forces act to shape each repertoire.

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The presence of autoantibodies to native and denatured collagen type II has been reported in some patients with rheumatoid arthritis (RA). This study examined the molecular nature of IgG binding to native and denatured collagen type II. The binding of IgG to native and denatured collagen was detected with an ELISA. Serum proteins were separated by size with gel filtration. Gel-filtered fractions were further characterized by binding to staphylococcal protein A. Among plasmas or serums from 60 patients with RA, 12 patients had IgG binding to native collagen type II and 12 had IgG binding to denatured collagen type II. Decomplementing normal serums by heating to 56 degrees C for 30 min markedly increased IgG binding to denatured collagen type II, but not to native collagen. This binding was shown to result from a complex formed between IgG and fibronectin. Nine unheated RA serums were separated by gel filtration. The IgG binding to native collagen was limited to monomeric IgG, but in these serums 65.6 +/- 22.0% of the IgG binding to denatured collagen type II was in the excluded protein fractions. The binding of IgG to denatured collagen type II in the excluded fractions was inhibited by fibronectin and did not bind to staphylococcal protein A. In patients with RA, the IgG binding to native collagen type II represents true autoantibodies. In contrast, in these patients the majority of IgG binding to denatured collagen type II is caused by macromolecular complexes formed between fibronectin and IgG or between fibronectin and IgG-containing immune complexes.

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