Receptors for IgA on human lymphocytes. II. Organ distribution and relationships with other Fc receptor-bearing populations

Lymphocyte populations expressing receptors for IgA (RFc alpha) in several human lymphoid tissues were numerically evaluated using a highly sensitive and specific indicator system. The percentages of RFc alpha-bearing lymphocytes were, in thymus, 9%; bone marrow, 14%; tonsil, 38%; cord blood, 34%; and adult blood, 55%. In adult and cord blood, RFc alpha were primarily associated with the T-lymphocyte populations as defined by their ability to bind sheep erythrocytes (SE). A large percentage of the peripheral T-lymphocyte population expressed both RFc alpha and receptors for IgM (RFcmu), whereas few T lymphocytes expressing receptors for IgG also displayed RFc alpha. Although a small number of peripheral non-T cells also expressed RFc alpha, they appeared to have fewer or less avid receptors than the RFc alpha-bearing T lymphocyte population. Both bone marrow and tonsil lymphocytes of both T and non-T populations expressed RFc alpha. Furthermore, the RFc alpha-bearing non-T population in both tonsil and bone marrow was quite large, 39 and 26%, respectively. These studies document the ubiquity of RFc alpha and its expression on the same peripheral lymphocyte population as RFcmu and indicate that RFc alpha is associated with several functionally different lymphocyte subpopulations including those involved in regulation (help) and antibody-dependent cell cytotoxicity.     

Expression of alpha-methylacyl-CoA racemase (P504s) in various malignant neoplasms and normal tissues: astudy of 761 cases

Alpha-methylacyl CoA racemase (AMACR), also known as P504S, plays an important role in peroxisomal beta-oxidation of branched-chain fatty acids. It has recently been shown that AMACR is highly expressed in prostate cancer and that it may be an important diagnostic marker for prostate carcinoma. However, little is known about expression of AMACR in normal tissues and other malignant tumors. In this study, we investigated expression of AMACR in 539 malignant tumors and 222 normal human tissues of various types by immunohistochemical analysis. mRNA levels of AMACR in normal organs and in selected tumors were assessed by real time PCR. In normal tissue, high expression of AMACR mRNA was identified in liver, kidney and salivary gland, while AMACR protein was detected in liver (hepatocytes), kidney (tubular epithelial cells), lung (only bronchial epithelial cells), and gallbladder (only mucosal epithelial cells). High expression of AMACR mRNA was found in prostate, liver, and kidney cancers but rarely in stomach and bladder cancers. A high percent of adenocarcinomas arising from these organs express AMACR, including 17 of 21 (81%) of hepatocellular carcinomas and 18 of 24 (75%) of renal cell carcinomas. In addition, carcinomas arising from tissues normally not expressing AMACR were also positive for the antigen, including 17 of 18 (94%) prostate carcinomas, 9 of 29 (31%) of urothelial carcinomas, and 4 of 15 (27%) of gastric adenocarcinomas. Two hundred and fifty cases of adenocarcinomas from lung, breast, pancreas, bile duct, adrenal gland, salivary gland, ovary, thyroid and endometrium were negative or rarely positive for AMACR. Neuroendocrine carcinomas rarely expressed AMACR. Melanomas, squamous cell carcinomas, basal cell carcinomas, soft tissue tumors (including epithelioid sarcomas and synovial sarcoma), thymomas, and germ cell tumors were negative for AMACR. Our data provide important baseline information for using AMACR in clinical practice and also are valuable in furthering understanding of the pathogenic role of AMACR in malignant neoplasms.     

VSGP/F-spondin: a new ovarian cancer marker.

The discovery of genes that are overexpressed in ovarian cancers provides valuable insight into ovarian cancer biology and will lead to the development of more effective treatment strategies for combating this disease. To identify genes exhibiting ovarian- and ovarian cancer-specific expression, we generated four subtracted cDNA libraries from primary and metastatic ovarian adenocarcinoma tissues. 3,400 cDNA clones from these libraries were analyzed by microarray for tissue distribution and tumor specificity using 32 pairs of fluorophore-labeled cDNA samples from a variety of normal tissues and ovarian tumor tissues. cDNA clones showing elevated expression in ovarian tumors were identified by DNA sequencing with comparison to public databases, and the most promising candidates were further analyzed by quantitative real-time polymerase chain reaction and Northern blot. This systematic approach led to the identification of a number of genes including vascular smooth muscle growth-promoting factor (VSGP/F-spondin), a secreted protein previously identified and cloned from bovine and human ovary. VSGP/F-spondin protein was observed in ovarian carcinomas but not in normal ovarian epithelium by immunohistochemistry with a VSGP/F-spondin antibody. The expression profile of VSGP/F-spondin identifies this molecule as a potential diagnostic marker or target for developing therapeutic strategies to treat ovarian carcinoma.     

The effects of recombinant-DNA-derived interferons on the growth of myeloid progenitor cells

Interferons (IFNs) have been shown to have significant effects on hematopoietic cell growth. Previous studies defining these effects have utilized mouse and human alpha-, beta-, and gamma-IFN isolated from supernatants of stimulated cells. Despite purification, the possible presence of other lymphokines and soluble factors remains a concern. In this study, the effects of gene-cloned alpha- and gamma-IFN on colony- forming units of granulocyte/macrophage (CFU-GM) progenitors cultured from the peripheral blood of normal volunteers were examined. In addition, blast cell colonies from one patient with acute myelogenous leukemia (AML) were studied. The growth of normal CFU-GM and AML blast cell colonies was inhibited in a dose-dependent manner by gamma- and alpha-IFN. gamma-IFN was ten to 100 times more potent than alpha-IFN in that this species of IFN reduced colony formation by greater than 50% at concentrations of less than 15 antiviral U/mL. The effects of gamma- IFN were neutralized by a monoclonal antibody specific for gamma-IFN. These in vitro studies indicate that human gamma-IFN may be an important modulator of myelopoiesis. Although these data indicate a possible efficacy of gamma-IFN in the treatment of AML, the in vitro results should be considered for their in vivo significance.     

Bispecific antibodies and targeted cellular cytotoxicity.

The Second International Conference on Bispecific Antibodies (BsAbs) and Targeted Cellular Cytotoxicity considered how targeted cytotoxicity can be used (1) to increase understanding of the general mechanisms of cellular cytotoxicity and (2) clinically in the treatment of cancer and infectious disease. BsAbs, the main mediators of targeted cellular cytotoxicity, can be made by chemical crosslinking, by fusing hybridoma cells and by molecular genetic approaches. BsAbs bind to target cells via one V region and trigger molecules such as T-cell receptors (TCRs) or FcR for IgG (Fc gamma R) on cytotoxic cells via their other V region. This linking of triggering structures to target cells induces target cell lysis and provides important clues to the signals used to elicit the lytic process.     

Expression of alpha-Methylacyl-CoA racemase (P504S) in atypical adenomatous hyperplasia of the prostate

Atypical adenomatous hyperplasia (AAH) of the prostate, also known as adenosis, is characterized by a proliferation of prostatic glands with abnormal architectural patterns, but without significant cytologic atypia. In some cases it may be difficult to distinguish AAH from prostatic carcinoma. Additionally, it is not clear whether AAH is a precursor lesion of prostatic adenocarcinoma. P504S, a protein highly expressed in prostatic adenocarcinoma, has been recently shown to be a marker of prostate cancer. The goal of this study is to examine the expression of P504S in AAH by immunohistochemistry. A total of 80 prostate specimens, including 40 cases of AAH (prostatectomy N = 30, biopsy N = 6, transurethral resection N = 4), 20 cases of prostatic adenocarcinomas, and 20 cases of benign prostatic hyperplasia, were studied. Immunohistochemistry for a prostate cancer marker alpha-methylacyl-CoA racemase (P504S) and a basal cell-specific marker 34betaE12 was performed in all the cases. The 34betaE12 stain confirmed the presence of patchy basal cells in all 40 cases of AAH. P504S was undetectable in the majority of AAHs (33 of 40, 82.5%), focally expressed in four of 40 (10.0%), or diffusely positive only in three of 40 (7.5%) cases of AAH. Interestingly, two of seven P504S-positive AAHs were found adjacent to adenocarcinoma. In contrast, all benign prostatic hyperplasias (20 of 20, 100%) were negative for P504S, and all 20 cases of prostatic carcinomas (100%) showed a diffuse P504S staining pattern. These findings suggest that AAH is a heterogenous entity. The biologic significance of P504S expression in a small subset of AAH remains to be determined. Because most cases of AAH are negative for P504S, immunostaining of P504S is also of diagnostic value in distinguishing the majority of AAHs from prostatic adenocarcinoma.     

Signal transduction pathways regulated by arsenate and arsenite

Arsenate and arsenite activate c-Jun N-terminal kinase (JNK), however, the mechanism by which this occurs is not known. By expressing inhibitory mutant small GTP-binding proteins, p21-activated kinase (PAK) and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinases (MEKKs), we have identified specific proteins that are involved in arsenate- and arsenite-mediated activation of JNK. We observe a distinct difference between arsenate and arsenite signaling, which demonstrates that arsenate and arsenite are capable of activating unique proteins. Both arsenate and arsenite activation of JNK requires Rac and Rho. Neither arsenate nor arsenite signaling was inhibited by a dominant-negative mutant of Cdc42 or Ras. Arsenite stimulation of JNK requires PAK, whereas arsenate-mediated activation of JNK was unaffected by inhibitory mutant PAK. Of the four MEKKs tested, only MEKK3 and MEKK4 are involved in arsenate-mediated activation of JNK. In contrast, arsenite-mediated JNK activation requires MEKK2, MEKK3 and MEKK4. These results better define the mechanisms by which arsenate and arsenite activate JNK and demonstrate differences in the regulation of signal transduction pathways by these inorganic arsenic species.