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Biomedical subjects

E M Hecht

Publications and source records attributed to E M Hecht.

5 recordsLinked to original sources
PubMed1992

Expression and gene transcript of Fc receptors for IgG, HLA class II antigens and Langerhans cells in human cervico-vaginal epithelium.

The mechanism of transmission of HIV from the male to the female genital tract or in the reverse order is not clear. CD4 glycoprotein is the receptor for HIV and Langerhans cells and the related dendritic cells could play a role in the initial transmission of HIV. Fc receptors (FcR) for IgG might be involved in antibody-mediated binding of HIV. We carried out an immunohistological study of normal human cervical and vaginal epithelia for the presence of CD4 glycoprotein, Langerhans cells and FcR to IgG. CD4+ glycoprotein was not found in the vaginal or cervical epithelium, with the exception of a few endocervical epithelial cells. A small number of CD4+ mononuclear cells were found in the endocervical epithelium of a third of the specimens but a large number of CD4+ cells was found in the submucosa of most of the cervical and vaginal specimens. Langerhans cells expressing CD4, HLA class II, Fc gamma R2 and Fc gamma R3 were detected in most vaginal, ectocervical and transformation zone epithelia and in 9/14 endocervical tissues. Fc gamma R3 was detected in about two-thirds of the columnar endocervical epithelium and the transformation zone. A smaller number of specimens expressed Fc gamma R2 in these epithelia, but Fc gamma R1 was not detected. We then demonstrated mRNA for Fc gamma R3 in the columnar endocervical epithelial cells and transformation zone by in situ hybridization, using a CD16-RNA probe. Fc gamma R3 and Fc gamma R2 gene transcripts were also found in fetal cervical tissue by applying the polymerase chain reaction to amplify portions of the Fc gamma R3 and Fc gamma R2 coding sequences in cDNA prepared from fetal RNA. HLA-DR was found in the endocervical cells, transformation zone and in Langerhans cells of all specimens. The presence of Langerhans cells, Fc gamma receptors and HLA class II antigen offers three potential mechanisms for cervico-vaginal HIV transmission: (i) direct HIV infection of Langerhans cells, (ii) binding of HIV antibody complexes to cervical epithelial Fc gamma receptors and (iii) binding of HIV infected CD4+ cells to cervical HLA class II antigen which may infect these or the adjacent CD4+ cells.

Adult↗
PubMed1991

Characterization of streptococcal antigen-specific CD8+, MHC class I-restricted, T cell clones that down-regulate in vitro antibody synthesis.

T cell clones were generated from the peripheral blood of rhesus monkeys that had been immunized with a soluble Mr 185,000 Ag (SAI/II) derived from Streptococcus mutans. The clones were CD3+ CD8+ CD4- alpha beta TCR+ and were specifically stimulated to proliferate by SAI/II. The proliferative responses of the cloned cells were class I restricted, as demonstrated by reconstitution of the cloned T cells with APC matched at various MHC class I and II loci, as well as by inhibition with anti-class I and not anti-class II mAb. The function of the CD8+ cloned cells was examined in vitro for their effect on antibody synthesis by Ag-stimulated CD4+ cells and B cells from immunized animals. Indeed, four of the five clones suppressed SAI/II-specific IgG antibody synthesis when activated with SAI/II and the appropriate MHC-matched APC. Although activation of the suppressor clones was Ag specific, the effector function of the suppression of antibody synthesis was Ag nonspecific. The latter was probably mediated by lymphokines and, indeed, the culture supernatant generated by stimulating the cloned CD8+ cells with anti-CD3 mAb suppressed both the specific and nonspecific antibody synthesis. Cytotoxicity studies showed that all five CD8+ clones showed a low level of lectin-dependent cytotoxicity. However, because four of the five clones expressed significant suppression of antibody synthesis, the suppressor activity was unlikely to be a function of the weak cytotoxicity. The results suggest that immunization of rhesus monkeys with a soluble streptococcal Ag induced CD8+ alpha beta TCR+ T cell clones that show SAI/II-specific, MHC class I-restricted proliferative responses and nonspecific down-regulatory function of in vitro antibody synthesis.

Animals↗
PubMed1991

The expression of Fc receptors for immunoglobulin G in human rectal epithelium.

The rectal mucosa is one of the routes of transmission of the HIV virus, although the mechanism of transmission is unknown. We carried out an immunohistological investigation of human rectal epithelium to detect CD4 glycoprotein and Fc receptors (FcR) for immunoglobulin G which may be involved in HIV infection. CD4 was not detected by monoclonal antibodies (MAb) in normal rectal epithelial cells, although CD4+ mononuclear cells were found in the lamina propria of the rectum. FcR3 and FcR2 were, however, detected in surface or crypt epithelial cells of rectal mucosa, using MAb to CD16 and CD32, respectively. In addition, CD16 messenger RNA (mRNA) was found in surface and crypt epithelial cells by in situ hybridization using an RNA probe. FcR3 and FcR2 were also detected in fetal recto-colonic tissue by immunohistology, suggesting that these are constitutive receptors. FcR3 and FcR2 gene transcripts were then demonstrated in fetal recto-colonic tissue using the polymerase chain reaction to amplify a portion of FcR3 and FcR2 coding sequences in complementary DNA (cDNA) prepared from fetal RNA. These findings suggest the possibility that rectal transmission of HIV-antibody complexes might be facilitated by the expression of FcR3 and FcR2 in rectal epithelial cells.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Human papillomavirus type 16 DNA expresses a replication modulation factor in cos-1 cells.

Plasmid DNA including the simian virus 40 (SV40) origin of replication undergoes uncontrolled, runaway replication in cos-1 cells owing to the intracellular production of SV40 large T antigen. Covalent linkage of such plasmids with human papillomavirus type 16 (HPV-16) DNA was found to prevent runaway replication. Replication control was found to be dependent on the presence of HPV-16 DNA sequences including the E1 open reading frame and part of the non-coding region.

Animals↗