Biomedical subjects

Carolyn Doyle

Publications and source records attributed to Carolyn Doyle.

3 recordsLinked to original sources

PubMed2002

Pulmonary surfactant proteins A and D directly suppress CD3+/CD4+ cell function: evidence for two shared mechanisms.

Pulmonary surfactant is a lipoprotein complex that lowers surface tension at the air-liquid interface of the lung and participates in pulmonary host defense. Surfactant proteins (SP), SP-A and SP-D, modulate a variety of immune cell functions, including the production of cytokines and free radicals. Previous studies showed that SP-A and SP-D inhibit lymphocyte proliferation in the presence of accessory cells. The goal of this study was to determine whether SP-A and SP-D directly suppress Th cell function. Both proteins inhibited CD3(+)/CD4(+) lymphocyte proliferation induced by PMA and ionomycin in an IL-2-independent manner. Both proteins decreased the number of cells entering the S and mitotic phases of the cell cycle. Neither SP-A nor SP-D altered cell viability, apoptosis, or secretion of IL-2, IL-4, or IFN-gamma when Th cells were treated with PMA and ionomycin. However, both proteins attenuated ionomycin-induced cytosolic free calcium ([Ca(2+) ](i)), but not thapsigargin-induced changes in [Ca(2+)](i). In summary, inhibition of T cell proliferation by SP-A and SP-D occurs via two mechanisms, an IL-2-dependent mechanism observed with accessory cell-dependent T cell mitogens and specific Ag, as well as an IL-2-independent mechanism of suppression that potentially involves attenuation of [Ca(2+)](i).

Amino Acid Sequence↗

PubMed2002

CD83 expression influences CD4+ T cell development in the thymus.

T lymphocyte selection and lineage commitment in the thymus requires multiple signals. Herein, CD4+ T cell generation required engagement of CD83, a surface molecule expressed by thymic epithelial and dendritic cells. CD83-deficient (CD83-/-) mice had a specific block in CD4+ single-positive thymocyte development without increased CD4+CD8+ double- or CD8+ single-positive thymocytes. This resulted in a selective 75%-90% reduction in peripheral CD4+ T cells, predominantly within the naive subset. Wild-type thymocytes and bone marrow stem cells failed to differentiate into mature CD4+ T cells when transferred into CD83-/- mice, while CD83-/- thymocytes and stem cells developed normally in wild-type mice. Thereby, CD83 expression represents an additional regulatory component for CD4+ T cell development in the thymus.

Adoptive Transfer↗

PubMed2002

Influence of CD4 T cells and the source of major histocompatibility complex class II-restricted peptides on cytotoxic T-cell priming by dendritic cells.

We have previously reported that bone marrow derived dendritic cells (DC) pulsed with major histocompatibility complex (MHC) class I-restricted peptide efficiently prime a cytotoxic T lymphocyte (CTL) response in vivo. Here we assess the involvement of CD4(+) T cells in the induction of CD8(+) CTL by DC by testing the ability of class II-deficient (C2D) DC, class II mutant (Alpha beta mut) DC and autologous serum generated DC (AS DC) to present class I-restricted antigens in vitro and in vivo. DC generated from the bone marrow of class II knockout mice and transgenic mice expressing a mutant class II that can not bind CD4 were phenotypically similar to wild type (wt) DC, except with regard to MHC class II expression. The C2D and Alpha beta mut DC, though fully capable of presenting the class I-restricted ovalbumin (OVA) peptide to a T-cell hybridoma in vitro, failed to prime a CTL response in vivo. Restoration of class II expression on C2D DC allowed priming of a CTL response; thus, the defect in CTL priming was indeed caused by the absence of class II expression. Likewise, DC generated in autologous serum were unable to prime a CTL response as these DC only express 'self' class II epitopes and therefore would not activate syngeneic CD4(+) T cells. Addition of exogenous class II epitopes rescued the ability of AS DC to prime a CTL response. These observations provide convincing evidence that efficient CTL induction by DC in vivo requires concomitant presentation of class II epitopes for CD4(+) T-cell induction.

Animals↗