Following thymic output, αβ⁺CD4⁺ T cells become activated in the periphery when they encounter peptide-major histocompatibility complex. A combination of cytokine and co-stimulatory signals instructs the differentiation of T cells into various lineages and subsequent expansion and contraction during an appropriate and protective immune response. Our understanding of the events leading to T-cell...

To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4(+) lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purifi...

Helper T cells play a crucial role in the induct ion and amplification of humoral and T cell-mediated immune responses in man. For example, helper T cells are absolutely required for the polyclonal immunoglobul in response triggered by pokeweed mitogen (PWM) (1) as well as for antigen-specific an t ibody responses to virus (2), soluble proteins (3), hapten (4), and heterologous erythrocytes (5)...

Signal transduction in response to ligand recognition by T cell receptors regulates T cell fate within and beyond the thymus. Herein we examine the involvement of the CD4 molecule in the regulation of T helper cell survival. T helper cells that lack CD4 expression are prone to apoptosis and show diminished survival after adoptive transfer to irradiated recipients. The helper lineage in CD4(-/-)...

A subunit vaccine for Plasmodium falciparum malaria will need to contain well-defined T helper cell epitopes that induce protective immune responses to the parasite. One major barrier to the use of subunit vaccines is the requirement for T helper cell epitopes to be presented by the HLA class II molecules that are present in the population being vaccinated. Since the majority of malaria studies...

The T helper paradigm is currently being revised from the Th1-Th2 dichotomy to a multi-state paradigm involving a number of different cell phenotypes. Transcriptional profiling using microarrays has been used to study the development of these phenotypes. There is however no clear consensus on how to approach the analysis of this data, especially in the context of cells that are triggered to exp...