Morphogenesis involves coordinated proliferation, differentiation and spatial distribution of cells. We show that lengthening of renal tubules is associated with mitotic orientation of cells along the tubule axis, demonstrating intrinsic planar cell polarization, and we demonstrate that mitotic orientations are significantly distorted in rodent polycystic kidney models. These results suggest that oriented cell division dictates the maintenance of constant tubule diameter during tubular lengthening and that defects in this process trigger renal tubular enlargement and cyst formation.

Borrelia isolates associated with Lyme borreliosis were previously divided into 3 genospecies, B. burgdorferi sensu stricto, B. garinii and group VS461, on the basis of DNA homology. B. burgdorferi sensu stricto and B. garinii were identified by monoclonal antibodies (MAbs), H3TS and D6 respectively, but no MAbs were available to identify group VS461. Two MAbs were produced, I 17.3 and J 8.3 which reacted with OspB and OspA proteins, respectively, of strains belonging to group VS461, which should be named B. afzelii sp. nov. 24 strains were assigned to B. afzelii sp. nov., 11 of them being isolated from skin lesions, 6 from acrodermatitis chronica atrophicans (ACA) and 5 from erythema chronicum migrans (ECM). Although quite unknown in the USA, ACA has frequently been reported in northern Europe where B. afzelii sp. nov. is commonly isolated. This study documents the involvement of B. afzelii sp. nov. as a specific aetiological agent of ACA.

Naturally occurring polyreactive anti-DNA mAbs derived from a nonimmunized (NZB ؋ NZW)F 1 mouse with spontaneous lupus erythematosus penetrated and accumulated in the nuclei of a variety of cultured cells. These mAbs and their F(ab)2 and Fab fragments, covalently coupled to f luorescein, peroxidase, or a 15-mer polynucleotide, also translocated to the cell nuclei. A 30-amino acid peptide corresponding to the combined sequences of the complementary-determining regions 2 and 3 of the heavy chain variable region of one mAb was able to penetrate into the cytoplasm and nucleus of cells of several lines. This peptide recognized DNA and was strongly polyreactive. Streptavidin-peroxidase conjugates complexed with the N-biotinylated peptide were rapidly translocated into cells. Similarly, peroxidase or antiperoxidase polyclonal antibodies covalently coupled to the N-cysteinylated peptide through an heterobifunctional maleimide cross-linker were also rapidly internalized and frequently accumulated in nuclei. The peptide carrying 19 lysine residues at its N-terminal was highly effective in transfecting 3T3 cells with a plasmid containing the luciferase gene. Thus, penetrating mAbs and derived peptides are versatile vectors for the intracellular delivery of proteins and genes.A long time ago, it was reported that human IgG from systemic lupus erythematosus patients with high titers directed against nuclear ribonucleoproteins and/or DNA were able to penetrate into living cells and to reach the nucleus (1). More recent studies of murine anti-DNA autoantibodies confirmed these observations and disclosed that different penetrating antibodies exhibited diverse behaviors and characteristics (2-7). In this study, we prepared several penetrating IgG anti-DNA mAbs from the spleen of a (NZB ϫ NZW)F 1 lupus mouse and examined their specificities and their abilities to act as vectors of haptens, proteins, polynucleotides, and plasmids. MATERIALS AND METHODSMice and Cell Lines. (NZB ϫ NZW)F 1 hybrids and BALB/c mice were bred in the Institut Pasteur animal facilities. Cells used were from different species and from various tissues as follows: PtK2 (Potoroo kidney fibroblasts) or CCL-39 (hamster lung), 3T3 (mouse embryo fibroblasts), and HEp-2 (human larynx carcinoma). All cells were from the American Type Culture Collection and were cultured in RPMI 1640 medium (or in DMEM for CCL-39) containing 10% heat-inactivated calf serum and supplemented with L-glutamine, sodium pyruvate, nonessential amino acids, and antibiotics (complete culture medium) at 37°C in a humidified atmosphere of 5% CO 2 /95% air.mAbs. Spleen cells from a 9-month-old nonimmunized (NZB ϫ NZW)F 1 mouse were fused with P3.X63Ag8 myeloma cells by the method of Köhler and Milstein (8), and hybridomas were selected in hypoxanthine/azaserine medium. Supernatants were tested by ELISA on double-stranded (ds) DNAcoated plates with ␤-galactosidase-labeled anti-Fc␥ conjugate prepared from sheep antiserum (9). Isotypes were determined by using anti-IgG1-, -IgG2a-, -IgG2b-,...

SummaryThe major mechanism by which bacteria acquire free or haemoglobin-bound haem involves direct binding of haem to speci®c outer membrane receptors. Serratia marcescens and Pseudomonas aeruginosa have an alternative system, which involves an extracellular haemophore, HasA, that captures free or haemoglobin-bound haem and shuttles it to a speci®c cell surface outer membrane receptor, HasR. Both haem-free (apoprotein) and haem-loaded (holoprotein) HasA bind to HasR, evidence for direct protein±protein interactions between HasA and HasR. HasA binding to HasR takes place in a tonB mutant. TonB is thus required for a step subsequent to HasA binding.

Crystallographic analysis of human Hfe has documented an overall structure similar to classical (class Ia) MHC molecules with a peptide binding groove deprived of ligand. Thus, to address the question of whether ␣␤ T cells could recognize MHC molecules independently of bound ligands, we studied human and mouse Hfe interactions with T lymphocytes. We provide formal evidence of direct cytolytic recognition of human Hfe by mouse ␣␤ T cell receptors (TCR) in HLA-A*0201 transgenic mice and that this interaction results in ZAP-70 phosphorylation. Furthermore, direct recognition of mouse Hfe molecules by cytotoxic T lymphocytes (CTLs) was demonstrated in DBA͞2 Hfe knockout mice. These CTLs express predominantly two T cell antigen receptor ␣ variable gene segments (AV6.1 and AV6.6). Interestingly, in wild-type mice we identified a subset of CD8 ؉ T cells positively selected by Hfe that expresses the AV6.1͞AV6.6 gene segments. T cell antigen receptor recognition of MHC molecules independently of bound ligand has potential general implications in alloreactivity and identifies in the Hfe case a cognitive link supporting the concept that the immune system could be involved in the control of iron metabolism. T cell receptor M ost histocompatibility class I molecules have an opengroove in their ␣1␣2-domains in which they bind peptides (HLA and H-2 class Ia molecules) less often than glycolipids (CD1 molecules) (1). The composite structures are recognized through their T cell antigen receptors (TCRs) by subsets of T lymphocytes [CD8 T lymphocytes, natural killer T cells (2), and mucosal associated invariant T cells (3)], resulting in cytolysis and͞or cytokine secretion, depending on the subset activated. Several TCR͞peptide͞MHC crystal structures have shown that the ␣1-and ␣2-helices of the MHC molecules are contacted by the TCR ␣-and ␤-chain complementarity-determining regions (CDR)1͞CDR2, the bound peptides interacting essentially with the hypervariable CDR3s (4). The dual selectivity of some alloreactive CTL clones for a given allogeneic molecule and a given peptide presented by this molecule might suggest that effective TCR͞MHC molecule interaction always requires a direct participation of the bound ligand (5, 6). However, less stringent peptide selectivity has been documented for other CTL clones (7,8), suggesting in those cases predominant TCR interaction with the ␣1␣2-helices of their allogeneic MHC molecular targets.Hfe is a nonclassical MHC class Ib molecule sharing 37% amino acid identity with HLA-A*0201. Hfe is formed, like classical MHC class I, by the noncovalent association of a heavy ␣ and a ␤2-microglobulin (␤2m) light chain (9). The 2.8-Å crystallographic structure of the human Hfe (hHfe) molecule has been published (10). Whereas its overall structure is similar to MHC class Ia molecules, Hfe has a narrow and empty version of the classical MHC class I peptide groove. To determine whether cytotoxic ␣␤ T cells are able to directly recognize the hHfe or mouse Hfe (mHfe), which are MHC class I molecules without an...