Analysis of Th1/Th2 Cytokine Profiles in Human Cd4 T Repertoire Specific for Pneumocystis

Pneumocystis carinii (Pc) is a fungus that cause severe pneumoniae (PCP) in immunocompromised hosts. Diverse functions of CD4+ T lymphocytes are needed to control this pathogen, as a TH1 type function e.g. the production of IFN-y upon antigen activation. Since in a previous work we showed a preservation of clonal heterogeneity of the PC specific CD4 T cell repertoire in HIV infected, asymptomatic individuals (Li Pira G., 2002), we have evaluated the possibility of expanding in vitro the PC specific repertoire for rat and human and to test them for cytokine potential in immunocompetent individuals. Antigen specific CD4 T cell lines were generated by repeated stimulation of PBMC with autologous irradiated PBMC as antigen presenting cells (APC), PC antigen (obtained from rats and humans with PCP) and IL-2. Proliferative response was used to determine the specificity of that T cell lines. For intacytoplasmic staining T cells were stimulated with PMA-ionomycin for 6 hours. The cells were collected, permeabilized and stained with the anticytokine fluorescent antibodies. Pc specific T cell lines were obtained from all immunocompetent subjects with both antigen preparations and compared for the response to different PC organisms. The lines obtained showed a high frequency of IFN-y producing cells that ranged from 50 to 80 %, while the frequency of IL-4 positive cells was more variable and ranged from 2 to 15%. Our data indicate that the lines showed a different fine specificities to regard to the used antigen for generating line. A typical TH1 profile was observed with both the antigens. Further studies to evaluated CD4+ repertoire in HIV + ves patients with two antigens are in progress.