[Clinicopathological and molecular genetic features of confined placental mosaicism].

Objective: To investigate the clinicopathological and genetic features of confined placental mosaicism (CPM) and its effect on fetal intrauterine growth. Methods: Fourteen CPM cases of Haidian Maternal and Children Health Hospital were collected from May 2018 to March 2022. Clinicopathological examination on placental specimens and molecular genetic analysis were performed. Results: The age of the parturient women ranged from 27 to 34 years, with an average age of (30.0±3.54) years. The gestational weeks ranged from 35+1 to 41+2 weeks. There were 4 premature births and 10 term births, among which 6 were female and 8 were male fetuses. Nine cases (9/14) had adverse pregnancy outcomes, including 7 cases of fetal growth restriction. The weight of CPM placenta decreased, with 6 cases below the 10th percentile of weight standards and 5 cases between the 10th and 25th percentile. All 14 CPM placental specimens showed morphological changes of perfusion dysfunction to varying degrees, with mainly placental-maternal vascular malperfusion followed by placental-fetal vascular malperfusion. The mosaic chromosomes in different CPM cases varied, with 16-trisomy/monosomy mosaicism being the most common followed by 7-trisomy and 21-trisomy/monosomy mosaicism. The mosaic proportion was unequal in different parts of the same CPM placenta, with the mosaic proportion of umbilical cord, fetal membranes, fetal surface, maternal surface, and edge ranging from 1% to 70%. Conclusions: The mosaic chromosomes in different CPM cases vary, and the mosaic proportion is unequal in different parts of the same CPM placenta. The pathological morphology is mainly manifested as perfusion dysfunction, which can lead to adverse pregnancy outcomes such as fetal growth restriction and preterm birth.

The association between nocturia, hormonal symptoms and bladder parameters in women: an observational study.

OBJECTIVE: Postmenopausal nocturia is poorly understood. This study aimed to identify hormonal and lifestyle factors associated with nocturia and to understand the relative contribution of altered urine production and bladder storage dysfunction in women. DESIGN, SETTING, POPULATION AND METHODS: Women ≥40 years presenting to public continence services were enrolled in a cross-sectional study. A total of 153 participants completed a hormone status questionnaire, a validated nocturia causality screening tool and a 3-day bladder diary. Descriptive statistics and logistic regression models for nocturia severity and bladder diary parameters were computed. RESULTS: Overall, 91.5% reported nocturia, 55% ≥2 /night. There was a difference of 167.5 ml (P < 0.001) in nocturnal urine volume between women with nocturia ≥2 (median 736 ml) versus less often (517 ml). Significant predictors of self-reported disruptive nocturia were age (odds ratio [OR] 1.04, 95% CI 1.002-1.073) and vitamin D supplementation (OR 2.33, 95% CI 1.11-4.91). Nocturnal polyuria was significantly more common with nocturia ≥2 compared with less frequent nocturia (P < 0.002). Exercise for 150 minutes a week was protective for nocturnal polyuria (OR 0.22, P = 0.001). Nocturia index >1.3 was significantly predicted by age (OR 1.07, P < 0.001), regular exercise (OR 0.41, P = 0.036), day flushes (OR 4.00, P = 0.013) and use of vitamin D (OR 2.34, P = 0.043). Maximum voided volumes were significantly lower with nocturia ≥2 versus less often (night: 268 ml versus 350 ml; day: 200 ml versus 290 ml). CONCLUSIONS: Bothersome nocturia in postmenopausal women is associated with changes to both nocturnal diuresis and bladder storage. Regular physical activity, prolapse reduction and oestrogen replacement may be adjunctive in managing bothersome nocturia in women.

[Singleton placentas with abnormal shape: a clinicopathological analysis of 130 cases].

Objective: To investigate the pathological characteristics of singleton placenta with abnormal shape and its influence on the outcome of maternal-fetal pregnancy. Methods: The clinicopathological data of singleton placentas with abnormal shape from January 2014 to December 2020 in the Department of Pathology, Haidian Maternal and Children Health Hospital were analyzed retrospectively. Results: There were 130 singleton placentas with abnormal shape in this cohort, including 48 succenturiate placentas, 12 bilobed placentas, 50 marginate placentas, 13 circumvallate placentas, 3 annular placentas, 2 membranous placentas and 2 fenestrated placentas. Gestational age ranged from 29+5 to 40+4 weeks. There were 51 cases of premature rupture of membranes, 11 cases of placenta previa, 5 cases of placental abruption, 15 cases of placental adhesion/implantation and 27 cases of postpartum hemorrhage. There were 46 preterm fetuses,28 fetuses with fetal growth restriction, 22 fetuses with intrauterine distress, and 1 fetus with intrauterine death. Grossly, the placental lobules of succenturiate placentas had apparent size difference, while two lobules of bilobate placenta were more consistent. The chorionic plate size was smaller than the bottom plate of circumvallate placenta, the folded fetal membrane in the rim of placenta was thickened (termed marginate placenta if there was no thickening). The membranous placenta was characterized by a thin, large membrane-like shape. Annular placenta showed characteristic hollow cylinder, ring or horseshoe-shape. Fenestrated placenta was characterized by tissue defects near central area. Microscopically, functional/morphologic changes were the main manifestations of inadequate maternal-fetal perfusion, including villous infarction, distal villous dysplasia and excessive villous maturation. Conclusions: The abnormal shaped singleton placentas showed variable extent of inadequate maternal-fetal perfusion, which may lead to adverse pregnancy outcomes such as premature delivery, fetal growth restriction, intrauterine distress or fetal death.

[Autopsies and placental examinations of perinatal fetal deaths: a clinicopathological analysis of 105 cases].

Objective: To summarize the clinicopathological factors related to perinatal fetal death and to evaluate importance of fetal autopsy and placental pathology. Methods: The clinicopathological data of 105 perinatal fetal deaths in Beijing Haidian Maternal and Child Health Hospital from November 2012 to December 2020 were retrospectively analyzed. Relevant literature was also reviewed. Results: The maternal age of the deceased fetuses ranged from 22 to 43 years with the average (31.35±4.04 years), and the gestational weeks were 28-40+6 weeks. Among them, 101 were singleton cases and 4 twin cases. 103 fetuses died in uterus and 2 died during delivery. Relevant factors analysis of the 105 perinatal fetal deaths showed that 86 cases (81.9%, 86/105) were related to umbilical cord/placental abnormality, 10 cases (9.5%, 10/105) uterine infection, 6 cases (5.7%, 6/105) fetal factors, 1 case was fetal maternal blood transfusion syndrome, 1 case twin blood transfusion syndrome, and 1 case died of complete uterine rupture. Among the 86 cases related to umbilical cord/placental abnormality, the diagnosis was most often based on the gross examination of placenta. The most common cause of death was umbilical cord torsion with thin root, followed by placental abruption, tight umbilical cord winding, vascular rupture and umbilical cord true knot. The morphology of placenta revealed mainly functional changes. Among the 10 cases related to intrauterine infections, the placenta generally showed lobular placental edema. The morphological characteristics of ascending infection were mainly acute chorioamnionitis, and the morphological characteristics of blood-borne infection were mainly acute or chronic villitis, as well as villous interstitial inflammation. Identification of viral inclusions suggested viral etiology, while the final diagnosis was relied on laboratory testing. Among the 6 cases related to fetal abnormality, the diagnostic value of placenta was limited and the diagnosis could be made with fetal autopsy. Conclusion: The causes of perinatal fetal death are complex, diverse, and often the synergistic result of multiple factors. Fetal autopsy and placental pathology are the key technical means to identify the cause of death and deserve more attention and utilization.

[Artificial intelligence aided measurement of cervical squamous epithelial thickness and its correlation with cervical precancerous lesions].

Objective: To study the thickness of cervical squamous epithelia and its correlation with cervical precancerous lesions. Methods: We selected 495 HE slides of 209 cervical biopsies from January 2020 to June 2020 in the Department of Pathology, the First and Seventh Medical Center of the PLA General Hospital, including 173 slides with low grade squamous intraepithelial lesion (LSIL) and 214 slides with high grade squamous intraepithelial lesion (HSIL). Artificial intelligence labeling software was used to assist in measuring the epithelial thickness of normal cervical squamous epithelium, LSIL and HSIL of each slide. The thickest, thinnest, and middle widths of epithelial thickness were measured, respectively. Average epithelial thickness was defined as the sum of the above three widths divided by 3. The correlation statistical analysis was performed by combining the data of age and pathological diagnosis. Results: The average thickness of normal cervical squamous mucosa was (245.83±91.40) µm, which was (222.42±81.22) µm and was (195.95±66.59) µm in LSIL and HISL epithelial respectively (F=27.09, P<0.01). The average cell layers of normal cervical squamous epithelium was (15.5±4.2) layers, which of LSIL was (14.8±4.8) layers, and that of HSIL was (15.8±4.8) layers. The differences among normal, LSIL and HSIL were not statistically significant (P>0.05). Further statistical analysis was stratified by age (≤30 years, 31-40 years, 41-50 years, 51-60 years, and >60 years), the results of Pearson correlation analysis showed that the thickness of normal cervical squamous epithelial gradually thinned with age (correlation coefficient r=-0.141 9, P<0.05), while LSIL and HSIL epithelial thickness had significant correlation with age (P>0.05). In the subgroup of ≤50 years old, the epithelial thickness of normal squamous epithelium was the thickest, followed by LSIL, and HSIL epithelial thickness was the thinnest. The differences were statistically significant (P<0.05). While in the subgroup of >50 years, the differences were not statistically significant (P>0.05). Conclusions: The cervical squamous epithelium gradually becomes thinner with the degree of precancerous lesions increasing among patients of ≤50 years old. However, after age of 50 years, with the onset of menopause, the normal mucosal epithelium is becoming atrophy, so that mucosal thickness is no longer correlated with the extent of the lesion. In addition, it is suggested that the cervical vinegar white test performance during colposcopy is related to the protein changes in the mucosal epithelial cells, but not directly related to the thickness of the epithelial layer.

Long-term Safety and Tolerability of Colesevelam HCl in Subjects with Type 2 Diabetes.

The bile acid sequestrant, colesevelam hydrochloride, is approved for glycemic control in adults with type 2 diabetes. In three double-masked, placebo-controlled studies, colesevelam hydrochloride 3.75 g/day demonstrated its glycemic-lowering properties when added to existing metformin-, insulin-, or sulfonylurea-based therapy in adults with inadequately controlled type 2 diabetes. This was a 52-week open-label extension study conducted at 63 sites in the United States and one site in Mexico to further evaluate the safety and tolerability of colesevelam hydrochloride in subjects with type 2 diabetes. All subjects who completed the three double-masked, placebo-controlled studies were eligible to enroll in this open-label extension. In total, 509 subjects enrolled and received open-label colesevelam hydrochloride 3.75 g/day for 52 weeks. Safety and tolerability of colesevelam hydrochloride was evaluated by the incidence and severity of adverse events. In total, 360 subjects (70.7%) completed the extension. Of the safety population, 361 subjects (70.9%) experienced an adverse event, most (88.1%) being mild or moderate in severity. Fifty-six adverse events (11.0%) were drug-related; the most frequent drug-related adverse events were constipation and dyspepsia. Thirty-five subjects (6.9%) discontinued due to an adverse event. Fifty-four subjects (10.6%) experienced a serious adverse event; only one was considered drug-related (diverticulitis). Seventeen subjects (3.3%) experienced hypoglycemia; most episodes were mild or moderate in severity. Glycemic improvements with colesevelam hydrochloride were seen without change in weight over 52 weeks (0.2 kg mean reduction from baseline). Colesevelam hydrochloride was safe and well-tolerated as long-term therapy for patients with type 2 diabetes.

Role of TLR4 for paclitaxel chemotherapy in human epithelial ovarian cancer cells.

BACKGROUND: Paclitaxel has been reported to be a ligand to Toll like receptor 4 (TLR4). Myeloid differentiation factor 88(MyD88) was described as a myeloid differentiation primary response gene. TLR4 signalling owns two pathways: MyD88-dependent and MyD88-independent pathways. XIAP is a key member of the inhibitor of apoptosis protein family. Akt is a major downstream target of growth factor receptor tyrosine kinases, which negatively regulates apoptotic pathways through phosphorylation (pAkt). The aim of the present study is to investigate the role of TLR4 in paclitaxel resistance of ovarian cancer cells. MATERIALS AND METHODS: We reconstructed the RNA interference expression vector, pGenesil-1-U6 specifically targeting TLR4 mRNA, which was stable transfected into the human ovarian cancer cell line SKOV3 (MyD88-positive expression) and A2780 (MyD88-negative expression). Cell proliferation, cell cycle distribution and cell apoptosis were assessed in the cells transfected with scramble control shRNA (SKOV3/shControl, A2780/shControl) and TLR4 shRNA (SKOV3/shTLR4, A2780/shTLR4) to explore the possible functions of TLR4 in ovarian cancer cells growth. The expression of TLR4, MyD88, XIAP, Akt and pAkt was analysed by Western blot analysis. RESULTS: A knockdown of TLR4 levels down-regulated the expression of XIAP and pAkt. And it restored the inhibitory effect of paclitaxel on cell proliferation and impeding cell cycle progression in SKOV3 cells. CONCLUSIONS: It suggests that TLR4 negatively regulates paclitaxel chemotherapy and MyD88 is an essential downstream factor to TLR4 signalling for this resistance. Knockdown of TLR4 induces paclitaxel chemosensitivity which might depress the Akt pathway. The TLR4-MyD88 signalling represents an important source to promote tumour growth.

Transferrin D1: identity in Australian aborigines and American Negroes.

Human transferrin D(1) obtained from an Australian aborigine was found to have the same substitution of glycine for aspartic acid in peptide 1C previously shown in transferrin D(1) from an American Negro. This finding is relevant to formation of distinct Australoid and African populations.

Hv(1), a variable-region genetic marker of human immunoglobulin heavy chains.

A new antigenic determinant was discovered with a hemagglutination-inhibition assay system. Designated Hv(1), it is located in the variable region of human immunoglobulin heavy chains of the G, M, and A classes. Pedigree and population analyses suggest that it has an autosomal dominant mode of inheritance. This represents the first description of an allotypic determinant in the variable region of human immunoglobulins.

Binding of human IgG myeloma proteins to autologous T-cell receptor determinants.

IgG myeloma proteins (MPs) produced by monoclonal plasma cells derived from B2 lymphocytes have been reported to bind to various autoantigens but the binding generally has been of low affinity. Moreover, T cells from some multiple myeloma patients can respond specifically to idiotypes of their own paraproteins. We analyzed the capacity of more than 20 human IgG MP to bind, a recombinant single-chain molecule containing complete V beta 8.1 and V alpha 1 structures, sets of synthetic peptide epitopes corresponding to a complete TCR beta chain, and a set of CDR1 epitopes corresponding to 24 human V beta gene products, and intact monoclonal T cells. Two of 20 MPs bound strongly to the recombinant TCR. Five of the same set, including these, bound to a synthetic epitope corresponding to the CDR1 segment. On a mass basis, the binding was approximately 1000-fold greater than that of pooled polyclonal IgG. The binding activity was confined to the Fab fragment and was specifically inhibitable by appropriate peptide determinants. Spectrotypic analysis using a set of CDR1 epitopes indicated that individual proteins showed characteristic binding patterns ranging from highly specific to relatively promiscuous. Highly reactive MPs also bound to TCR on intact cells in immunocytofluorescence by flow cytometry. These results are consistent with the relatively frequent occurrence of autoantibodies to TCR determinants and indicate that MPs can be derived from this autoantibody subset.

Restriction of C1 hemolytic function by human proline-rich salivary proteins.

Acidic proline-rich salivary proteins, PRPI, PRPII, PRPIII, PRPIV, upper Db and Statherin, were isolated from parotid saliva and tested for interaction with complement. It was determined that each of the isolated proline-rich proteins blocked C1 hemolytic activity in assay systems where C1 was rate-limiting. Further studies comparing the specific activity of the proline-rich proteins to unfractionated parotid saliva indicated that other salivary substances (sensitive to urea treatment of parotid saliva) were also interacting with the first complement component but in a time-dependent manner. Based on a series of experiments examining the effect of the sequence of addition of the proline-rich proteins in the complement assay systems, it is postulated that these salivary proteins are able to block the proper interaction of C1 with EAC4 cells (sheep erythrocytes coated with antibody and C4gp). The proline-rich salivary proteins had no effect on C1 once C1 was bound to the immune complexes on the EAC4 cells. The C1 macromolecular complex undergoes conformational changes upon interaction with immune complexes resulting in a more avid binding of the C1q-Clr-Cls subunits with one another. Thus it is speculated that the EAC4-bound C1 becomes resistant to disruption by the proline-rich salivary proteins. Although the urea-sensitive factors had the highest specific C1-fixing activity, the activity of the acidic proline-rich proteins on C1 is important because of their relatively high concern in salivary secretions. Since complement-containing serous exudates and transudates are present on inflamed mucosal tissues, salivary substances which interact with C1 may play a role in regulating the initiation of the classical complement pathway, particularly at those mucosal sites where there is a high ratio of salivary secretion to serous exudate.

Identification and characterization of Thy-1 homologues from bovine thymocytes.

Two forms of Thy-1 homologues of apparent mol. wt of 25,000 (designated BTp25) and 45,000 (designated BTp45) were isolated from bovine thymocyte membrane by solubilization, affinity chromatography with Con A, and preparative SDS-PAGE. Both forms reacted with a rabbit antiserum to murine Thy-1 in an enzyme-linked immunosorbent assay (ELISA). BTp45 is most likely a dimer of BTp25, since the two are indistinguishable in their amino acid compositions. Comparison of amino acid compositions of BTp25 and BTp45 to that of rodent and human Thy-1 by the S delta Q index revealed significant relatedness among these molecules. BTp25 and BTp45 demonstrate more structural homology to rodent Thy-1 than to human Thy-1. Detailed chemical analyses indicate that bovine Thy-1 homologues contain neutral sugars and fatty acids covalently bound to the polypeptide chain; therefore, they are lipoglycoproteins.

Molecular comparison of mouse Thy-1 and its human homologue.

Physicochemical techniques were used to verify previous immunochemical studies showing homology of the human Thy-1 (formerly p25) antigen and the murine Thy-1 or theta antigen. Peptide maps and amino acid compositions showed close similarity between these two proteins; however, they were not identical. These data confirm that the p25 antigen is the human homologue of mouse Thy-1.

Molecular basis for the temperature-dependent insolubility of cryoglobulins--XI. Sequence comparison of the heavy-chain variable regions of the human cryoimmunoglobulins McE and Hil by metric analysis.

The amino acid sequences of the VH-domains from two human cryoimmunoglobulins have been compared with one another and with the VH-domains of noncryoglobulins by the mathematical method of metric analysis. The VHII sequence of McE [Gerber-Jenson et al. (1981), J. Immun. 126, 1212-1216] and the VHIII sequence of Hil [Chiu et al (1979), Biochemistry, 18, 553-560] resemble much more closely the VH-sequences of noncryoglobulins from their own subgroups than they resemble one another. Neither cryoglobulin sequence contains an unusual insertion or deletion of residues. Based on the crystallographic structure of the VHII domain in the Fab fragment of the human noncryoglobulin Newm [Saul et al. (1978), J biol. Chem., 253, 585-597], McE and Hil each contain two unprecedented residues in the outer beta-sheet structure of the VH-domain. The inwardly directed sidechains of Gly-71 and Ile-84 in McE may perturb the internal hydrophobic interactions and normal folding of adjacent segments of the outer beta-sheet from the third framework region. In contrast, the outwardly directed sidechains of Ile-23 and Arg-77 in Hil may perturb the external hydrophilic properties and folding of adjacent segments of the outer beta-sheet from the first and third framework regions. Thus, the monoclonal immunoglobulins McE and Hil may display cold-induced insolubility by different perturbations of the outer surface of the VH-domain. In each case, the unprecedented framework residues that mnay be responsible could have arisen by two point mutations involving single base changes.

Antibodies to synthetic peptides corresponding to variable-region first-framework segments of T cell receptor. Detection of T cell products and cross-reactions with classical immunoglobulins.

Recent studies at the gene level have shown that T cells express rearranged genes for four types of T cell receptors that are strongly homologous to classical immunoglobulins in the joining region and in the framework 1 (Fr1) and 3 segments of the variable region. Based upon the homologies in gene sequence, it follows that the gene products would show similarities in amino acid sequence and in the folding of the proteins so that cross-reactivities in antigenic determinants would be expected between variable regions of the T cell receptors and classical immunoglobulins. We have synthesized peptides corresponding to predicted protein sequences of the Fr1 residues of T cell receptor alpha, beta- and gamma-chains and have produced antibodies in rabbits against these synthetic peptides. Use of antisera and affinity-purified antipeptide antibodies indicated that high-titer antibodies could be raised that were specific for individual Fr1 peptides. Cross-reactions among Fr1 peptides of T cell receptors and immunoglobulin light chains were observed. In addition, some rabbit antisera raised against classical polyclonal immunoglobulins or affinity-purified immunoglobulin-like T cell receptors were found to exhibit binding activity against Fr1 peptides of T cell receptor beta- and gamma-chains. The sequence homology, although real among the Fr1 of T cell receptors and immunoglobulin light chains, is moderate and the antigenic cross-reaction must reflect the configuration and types of amino acids present. The development of antipeptide antibodies holds promise for the characterization of T cell receptors of various T cell sources and also offers a new means for the identification of molecules related to rearranging immunoglobulins.

Identification of Thy-1 homologue in rabbit brain by immunoblot, immunohistochemistry and DNA/DNA hybridization.

A membrane glycoprotein with an apparent molecular weight of approximately 26,000 reacted on immunoblot with a monoclonal antibody (HB-3S-17) directed toward human Thy-1. At cellular level, HB-3S-17 reacted with both rabbit and human cerebral cortexes in a similar manner as demonstrated by immunohistochemical staining. Screening of a rabbit brain expression cDNA library with HB-3S-17 resulted in the isolation of a clone designated RBT-2A-1. The rabbit cDNA insert of RBT-2A-1 hybridized in Southern blot with an oligonucleotide probe derived from the mouse Thy-1.2 gene. These data strongly indicate the existence of a glycoprotein in rabbit brain which is the counterpart of human and mouse Thy-1.

Expression of the Thy-1 gene in human T lymphoid cell lines.

We have previously shown that three human T cell lines (MOLT-3, HUT-78 and HUT-102) were able to react with anti-human brain Thy-1 sera by cell surface immunofluorescence. However, the possibility that the antisera might cross-react with molecules other than Thy-1 could not be entirely excluded. In this report, mRNA prepared from these three T cell lines as well as from a murine T cell line (EL4) and a human B cell line (Raji) was subjected to Northern blot analysis and probed with a murine Thy-1.2 gene fragment. The result confirms our cell surface immunofluorescence data and indicates that HUT-78 and HUT-102 cells have approximately 20-fold more of the Thy-1 mRNA than MOLT-3 cells do. The Thy-1 mRNA was not detectable in the human B cell line Raji. This work is the first demonstration that the Thy-1 gene is expressed in human T cell lines. The finding is helpful in clarifying the current confusion regarding the expression of Thy-1 in human lymphoid cells and it also provides a possible model system for exploring the function of Thy-1 in cultured human T lymphocytes.

Partial characterization of immunoglobulin light chains of carcharhine sharks: evidence for phylogenetic conservation of variable region and divergence of constant region structure.

Isolated light chains of IgM-type immunoglobulins of carcharhine sharks were analyzed by serological and biochemical means. When analyzed by isoelectric focusing analysis, light chains of the tiger shark (Galecerdo cuvieri), the galapagos shark (Carcharhinus galapagensis) and the sandbar shark (Carcharhinus plumbeus) showed a broad, but patterned, spectrum of bands ranging from pI 5.0 to 7.7 in which discrete families were observed. Serologically, light chains of the galapagos shark cross-reacted with rabbit antibodies against mouse immunoglobulin and a synthetic peptide corresponding to the J segment of T cell receptor beta chain. The latter cross-reaction is shared among light chains and T cell receptors. Although there was considerable heterogeneity in isoelectric focusing analysis, the light chains were homogeneous on the basis of apparent mass (23 kDa) and those of tiger shark and galapagos shark had relatively homogeneous dominant N-terminal sequences representing the first framework. The N-terminal sequences of these two shark light chains, were strongly homologous to one another and showed 75% identity to certain V kappa sequences of man and dog. Homology was also shown to V lambda sequences, but the degree of identity was approximately 50%. Following cleavage of the tiger shark light chain with o-iodosobenzoic acid which cleaves at tryptophanyl residues, a constant region peptide was isolated by gel filtration. It was possible to identify the homolog of this peptide within the constant regions of mammalian kappa and lambda chain, but the relationship to C kappa chain was stronger. The degree of identity among the corresponding C region peptides of mammalian, avian and elasmobranch species was much less than that observed for the framework 1 sequence of the light chain variable region. These data support the concept that variable and J region sequence have been conserved in the evolution of placoderm-derived vertebrates, but that constant regions show much greater phylogenetic variation.

Antigenic determinant(s) shared by the human Thy 1 and human IgG.

A human T cell differentiation antigen (p25) previously described as being the mouse theta equivalent has been examined for shared antigenic determinants with immunoglobulin. A strong cross-reactivity of an antiserum prepared against p25 antigen was established with human IgG subclasses. This antiserum does not react with human IgM or IgA, nor with primate immunoglobulins. The shared determinants appear to be associated with the disulphide-bonded cysteines in the first and third constant domains of the IgG molecule and the 9-112 disulfide bond of Thy 1.