Primary cells and established cell lines join DNA ends with the same efficiency relative to homologous recombination

The joining of DNA ends was compared in the established CV1 cell line and in African green monkey kidney primary cells, from which the CV1 cell line was established. Using a linear SV40 genome that carries a terminal repeat of 526 nucleotide pairs, we measured the efficiency of circularization by end joining relative to circularization by homologous recombination between the terminal repeats. The ratios of end joining to homologous recombination were identical in the two types of cells regardless of whether the DNA ends were sticky, blunt, or mismatched. These studies demonstrate that the efficient end joining observed in established cell lines is not a peculiar adaptation to life in culture, but rather reflects a normal aspect of DNA metabolism in mammalian cells. Furthermore, the similar results in primary and established cells support the general validity of using data from studies of cultured cells to formulate models of recombinational processes in primary cells and potentially in multicellular organisms as well.

Specific inhibition of cell-surface T-cell receptor expression by antisense oligodeoxynucleotides and its effect on the production of an antigen-specific regulatory T-cell factor

We have used antisense oligodeoxynucleotides corresponding to genes encoding the variable (V) region of the T-cell receptor (TCR) alpha and beta chains (V alpha and V beta) to control TCR expression in T-cell hybridomas. Two hybridomas, A1.1 and B1.1, recognize a synthetic polypeptide antigen designated poly 18 (poly[Glu-Tyr-Lys-(Glu-Tyr-Ala)5]) together with I-Ad. We have found that TCR function (production of lymphokines in response to antigen) and T3 expression were removed after protease treatment of the cells and were fully recovered 48 hr later. However, when antisense oligodeoxynucleotides corresponding to the appropriate TCR V genes were present after protease treatment, little or no recovery of TCR function or T3 expression was observed. This effect was specific for the TCR V genes utilized by the T cell: antisense oligodeoxynucleotides corresponding to the TCR V regions of A1.1 had no effect on TCR expression in B1.1 and vice versa. Thus, antisense oligodeoxynucleotides can be used to temporarily block expression of a TCR gene in a T-cell hybridoma. This technique was then applied to a paradoxical phenomenon in A1.1 cells. We had observed previously that A1.1 releases an antigen-specific immunoregulatory activity that shows the same antigenic fine specificity as is displayed by the TCR of A1.1. We now report that antisense oligodeoxynucleotides corresponding to the A1.1 V alpha gene blocked the production of this soluble antigen-specific activity by the cell. Antisense oligodeoxynucleotides corresponding to A1.1 V beta, on the other hand, had no effect on the production of this antigen-specific activity. We discuss these observations in the context of recent findings on the nature of T cell-derived antigen-specific regulatory factors.

An antigen-specific helper T cell hybridoma produces an antigen-specific suppressor inducer molecule with identical antigenic fine specificity. Implications for the antigen recognition and function of helper and suppressor inducer T cells

We have previously described a T cell hybridoma, A.1.1, that responds to specific Ag (P18, a synthetic polypeptide of defined sequence) in the context of I-Ad by producing lymphokines. Herein we report that this cell also releases, into culture supernatants and ascites fluid, an Ag-specific activity that functions in the induction of suppression of anti-SRBC PFC responses. This suppressive activity requires a) Ag-non-specific accessory molecules from a T suppressor inducer factor, b) Ly-2+ T cells in the assay cultures, and c) the specific Ag (P18) conjugated to the SRBC in the assay cultures. The specificity of the A.1.1-derived activity was demonstrated by the absence of suppression in cultures containing SRBC, BSA-SRBC, or conalbumin-SRBC rather than P18-SRBC. Further, the A.1.1-derived activity bound to, and could be eluted from, P18 but not conalbumin. Using a panel of synthetic variant peptides, we have mapped the critical residues in P18 required for Ag/I-Ad induced activation of A.1.1. These peptides were tested for their ability to act as targets for the A.1.1-derived suppressive activity when conjugated to SRBC and added to assay cultures. All peptides capable of stimulating the A.1.1 T cells to release lymphokines were similarly effective in the suppressor assay. Thus, the recognition of Ag by the T cells and by the T cell-derived activity appeared to be identical. The A.1.1-derived molecule was found to be capable of inducing L3T4- T cells to act as suppressor T cells following culture. These suppressor cells were active in inhibiting anti-SRBC responses in the absence of P18 and bore the Ly-2 surface marker. Thus, it is likely that the function of this Ag-specific molecule is to induce Ly-2+ suppressor T cells and thereby cause the inhibition of the response. This function is distinct from that normally associated with helper T cells and may shed new light on the possible relationship between the cell surface T cell receptor for Ag and Ag-specific T suppressor inducer molecules.

An antigen-specific helper T cell hybridoma produces an antigen-specific suppressor inducer molecule with identical antigenic fine specificity. Implications for the antigen recognition and function of helper and suppressor inducer T cells

We have previously described a T cell hybridoma, A.1.1, that responds to specific Ag (P18, a synthetic polypeptide of defined sequence) in the context of I-Ad by producing lymphokines. Herein we report that this cell also releases, into culture supernatants and ascites fluid, an Ag-specific activity that functions in the induction of suppression of anti-SRBC PFC responses. This suppressive activity requires a) Ag-non-specific accessory molecules from a T suppressor inducer factor, b) Ly-2+ T cells in the assay cultures, and c) the specific Ag (P18) conjugated to the SRBC in the assay cultures. The specificity of the A.1.1-derived activity was demonstrated by the absence of suppression in cultures containing SRBC, BSA-SRBC, or conalbumin-SRBC rather than P18-SRBC. Further, the A.1.1-derived activity bound to, and could be eluted from, P18 but not conalbumin. Using a panel of synthetic variant peptides, we have mapped the critical residues in P18 required for Ag/I-Ad induced activation of A.1.1. These peptides were tested for their ability to act as targets for the A.1.1-derived suppressive activity when conjugated to SRBC and added to assay cultures. All peptides capable of stimulating the A.1.1 T cells to release lymphokines were similarly effective in the suppressor assay. Thus, the recognition of Ag by the T cells and by the T cell-derived activity appeared to be identical. The A.1.1-derived molecule was found to be capable of inducing L3T4- T cells to act as suppressor T cells following culture. These suppressor cells were active in inhibiting anti-SRBC responses in the absence of P18 and bore the Ly-2 surface marker. Thus, it is likely that the function of this Ag-specific molecule is to induce Ly-2+ suppressor T cells and thereby cause the inhibition of the response. This function is distinct from that normally associated with helper T cells and may shed new light on the possible relationship between the cell surface T cell receptor for Ag and Ag-specific T suppressor inducer molecules.

Reliability and validity of a Chinese computerized diagnostic instrument

This paper reports on the development and testing of a new Chinese diagnostic instrument--the Adult Diagnostic Interview Schedule-Present (ADIS-P). This instrument uses a selection of items adapted from DIS and SADS. It is administered within approximately 25 min by a trained clinician using a small portable computer that provides an immediate diagnosis. The instrument was tested on 1,331 patients from six large mental hospitals across the country. The concurrent validity was good: compared to the concensus diagnosis of two senior clinicians (who were blinded to the ADIS-P result), the overall diagnostic accuracy was 83% and the weighted Kappa value was 0.60. The 1 month test-retest reliability was satisfactory (weighted Kappa = 0.55). We conclude that ADIS-P is a convenient, reliable and valid diagnostic instrument.

A suppressor-inducer factor produced by burn trauma-associated T cells

Six days after a full-thickness scald burn in specific-pathogen free mice, potent suppressive activity was observed in the serum and in supernatants of splenic T cells. The serum activity could be blocked by addition of a monoclonal anti-T suppressor molecule antibody to assay cultures. An examination of the six-day postburn T cell supernatants revealed suppressor inducer T cell (Tsi) activity with a number of characteristics of other Tsi factors described in other systems. These observations further implicate the suppressor T cell pathway in the immunoregulatory sequelae of severe thermal trauma.