Treatment of (NZB x NZW)F1 disease with anti-I-A monoclonal antibodies.

(NZB x NZW)F1 mice spontaneously develop an autoimmune syndrome characterized by a fatal immune complex glomerulonephritis. Administration of monoclonal antibodies specific for an I region gene product (I-Az) of the H-2 haplotype associated with susceptibility to glomerulonephritis in these animals produced a remission in female mice with established renal disease. The results demonstrated that anti-I-A therapy stabilized the level of proteinuria and increased the 1-yr survival rate from 10% to greater than 90% in treated animals relative to control mice. These findings may ultimately have therapeutic potential for the treatment of systemic lupus erythematosus.

Overexpression of p53 in head and neck cancer.

The putative tumor suppressor gene p53 plays a key role in the regulation of cell proliferation. Functional loss of p53 protein through mutation or viral oncogene-complexing can result in p53 protein overexpression detectable by immunocytochemistry, which in turn has been associated with markers of poor prognosis in some cancers. We report here an analysis of p53 overexpression in fixed, embedded specimens from 81 prospectively collected head and neck tumors, both benign and malignant, including 55 squamous cell carcinomas, using monoclonal pAb1801. Sixty-two percent of the squamous cell carcinomas from the head and neck region overexpressed p53, whereas none of the benign tumors or adjacent normal tissues overexpressed p53. Overexpression of p53 was strongly associated (p < 0.01, two-tailed chi-square) with a histologic malignancy grading scale previously shown to have prognostic capabilities. We conclude that p53 overexpression is one of the most common abnormalities identified in head and neck cancer, and may be a useful marker in the study of multistep progression of tumorigenesis.

Identification of hair cell progenitors and intermitotic migration of their nuclei in the normal and regenerating avian inner ear.

Postembryonic production of sensory hair cells occurs in both normal and aminoglycoside-damaged avian inner ears. The cellular source and mechanism that results in new differentiated hair cells were investigated in the avian vestibular epithelia using three distinct cell-cycle-specific labeling methods to identify proliferating sensory epithelial cells. First, immunocytochemical detection of the proliferating cell nuclear antigen, an auxiliary protein of DNA polymerase, allowed labeling of cells in late G1, S, and early G2 phases of the cell cycle. Second, a pulse-fix tritiated thymidine autoradiographic protocol was used to identify cells in S phase of the cell cycle. Finally, Hoechst 33342, a fluorescent DNA stain, was used to identify epithelial cells in mitosis. The distribution of cells active in the cell cycle within the normal and ototoxin-damaged vestibular epithelium suggests that supporting cells within the sensory epithelia are the cellular precursors to the regenerated hair cells. Differences between the proliferation marker densities in control and damaged end organs indicate that the upregulation of mitotic activity observed after streptomycin treatment is due primarily to an increase in the number of dividing progenitor cells. The differences between the extent of ototoxic damage and the level of reparative proliferative response suggest a generalized stimulus, such as a soluble chemical factor, plays a role in initiating regeneration. Finally, after DNA replication is initiated, progenitor cell nuclei migrate from their original location close to the basement membrane to the lumenal surface, where cell division occurs. This pattern of intermitotic nuclear migration is analogous to that observed in the developing inner ear and neural epithelium.

Characterization of two distinct DR beta chain alleles at the beta III locus of the DR5 haplotype: beta III alleles are highly conserved.

The HLA-DR beta region of at least two members of the DRw52 (MT2) supertypic group (DR3, DR5, DRw6, and DRw8) has recently been shown to contain three beta-chain genes--beta I, beta II, and beta III, ordered in the direction of transcription. beta III is apparently a duplication of beta I. Both beta I and beta III are expressed, whereas beta II is a pseudogene. We previously reported the sequence of the DR5 beta I cDNA from the homozygous DR5 cell line Swei. We report here the sequence of two different DR5 beta III cDNA from the same cell line. The assignment of the genes of this and other members of the DRw52 supertypic group to specific loci allow comparisons between products of known alleles and between products of distinct loci. beta I allelic products showed approximately 11% divergence in the first domain, whereas beta I and beta III products showed 17% difference. These differences were clustered and found predominantly in the previously described variable regions (amino acid residues 9 through 13, 26 through 38, and 67 through 74). These data, coupled with the finding of shared variable regions among different DR beta chains, suggest gene conversion as a means of generating polymorphism in the beta I alleles. In contrast, the beta III allelic products showed less than 1% amino acid and nucleotide divergence in the first domain. These differences were outside the variable regions, and attributable to single nucleotide changes. The polymorphism at the beta I locus and the conservation at the beta III locus suggest selective pressure conserving the beta III locus and/or generating polymorphism at the beta I locus, and further suggest that gene conversion may be acting unidirectionally from beta III to beta I.

DNA sequence and characterization of human class II major histocompatibility complex beta chains from the DR1 haplotype.

Two HLA class II beta-chain clones from a cell line homozygous for the DR1 haplotype have been characterized and sequenced. They represent a DR beta chain (2918.4) and a DQ beta chain (2918.8). Clone 2918.4 has been used to select mRNA from a lymphoblastoid cell line, and this was injected into Xenopus oocytes with mRNA selected with a DR alpha chain. The translation products were immunoprecipitated with a beta-chain-specific monoclonal antibody and electrophoresed on two-dimensional gels. This revealed positive signals in the positions predicted for beta and alpha chains. Sequence comparisons of 2918.4 with previously published DR beta-chain sequences confirm the presence of two regions of variability in the membrane distal domain. Analysis of the sequence of 2918.8 identified it as a DQ beta chain identical to one previously published from a DR3,w6 cell line. We speculate, therefore, that the DQ beta sequence represents the DQ1 specificity shared by the DR1 and DRw6 haplotypes.