Autoantibody to the proliferating cell nuclear antigen neutralizes the activity of the auxiliary protein for DNA polymerase delta

Two murine monoclonal antibodies to the proliferating cell nuclear antigen (PCNA), a rabbit anti-N-terminal peptide antibody and human auto-antibody to PCNA reacted with the auxiliary protein for DNA polymerase delta from fetal calf thymus following SDS-polyacrylamide gel electrophoresis, confirming the identity of PCNA and the auxiliary protein. Undenatured auxiliary protein was immunoprecipitated by the human autoantibody, but not by the monoclonal antibodies, which were raised to SDS-denatured PCNA, nor by the anti-N-terminal peptide antibody, suggesting that the epitopes recognized by both the monoclonal antibodies and the anti-peptide antibody are not exposed in the native protein. The human anti-PCNA autoantibody neutralized the activity of the auxiliary protein for DNA polymerase delta, but did not inhibit the activity of pol delta itself. The ability of pol delta to utilize template/primers containing long stretches of single-stranded template was inhibited by the anti-PCNA autoantibody, whereas the activity of pol alpha on such templates was not affected, confirming the specificity of the auxiliary protein for pol delta. The ability of PCNA, a cell cycle-regulated protein, to regulate the activity of pol delta suggests a central role for pol delta in cellular DNA replication.

Determination of antibodies in dried blood from earlobes of leprosy patients by enzyme-linked immunosorbent assay--a preliminary report

An enzyme-linked immunosorbent assay (ELISA) was used with soluble antigens of Mycobacterium leprae. All blood samples collected from the earlobes of 109 leprosy patients and 100 healthy controls (from a non-endemic area of leprosy) were absorbed with M. vaccae, BCG, cardiolipin, and lecithin according to the technology of the FLA-ABS test before being tested in the ELISA. The results (at a 1:200 blood dilution) showed that antibody activity gradually increased from TT to LL (mean OD values: TT = 0.43, BT = 0.62, BB = 0.72, BL = 0.84, LL = 0.89), and the rates of positive reactions were 100% in all classifications of patients except TT (66.6%). Antibody activity in the controls was less pronounced than in leprosy patients, their mean OD value being only 0.15. We suggest that the ELISA is highly sensitive and specific for the determination of anti-M. leprae antibodies, and is useful for clinical serodiagnosis and for the study of subclinical infections in leprosy.

Nuclear pore complex in spermatogenesis of Beijing domestic duck. Electron microscope observation of freeze-etching

The nuclear pore complex in spermatogenesis of Beijing domestic duck has been studied by means of electron microscopic observation of freeze-etching. The structure of the pore observed proves to be in accord with the model of the nuclear pore complex proposed respectively by Franke (1970) and Roberts et al. (1970). But its central granule may be present (1-3 granules) or absent. The granules are considered to be material in transit. The size and frequency of the pore vary with different types of reproductive cells, which is believed to be related to the cells' function. The pores concentrate on the side of nucleus near Golgi zone in primary spermatocyte and near the proacrosome of spermatid, and this shows the functional variety of parts in the nucleus.

Natural antibodies against a polysaccharide (Bo) from sugar cane mediate its complement-activating effect

The interaction of a complement activating glucan from sugar cane (Bo) with immunoglobulins was studied. Bo precipitates a small fraction of IgG from human serum. In combination with this fraction, it activates complement by the classical pathway, not in its absence. Bo is adsorbed to and can be eluted from Sepharose containing covalently coupled IgG; it is not bound when the IgG-Sepharose is lacking the Bo-reactive IgG fraction. Bo-IgG complexes activate and fix C1. The binding of C1 to aggregated IgG is not inhibited by Bo. This is in contrast to the strong inhibition of C1 fixation by the Fc-binding protein A. It is concluded that normal human serum contains natural antibodies against Bo which form complement-activating immune complexes with Bo by binding it to their F(ab) region. The antibodies do not cross-react with dextran, a glucan from barley, nor with surface constituents of E. coli.