Adoptive transfer of experimental hypersensitivity pneumonitis: CD4+ cells are memory and naive cells

We previously demonstrated that CD4+ cells are responsible for transfer of adoptive murine experimental hypersensitivity pneumonitis. To further characterize the CD4+ cells as naive or memory cells, we depleted Micropolyspora faeni-sensitized cultured C3H/HeJ spleen cells of surface IgM+ cells by panning and Ia+ cells by lysis. We measured the proportion of CD4+ cells that expressed CD45RB, CD44 or LECAM-1 (markers used to distinguish memory from naive CD4+ cells) in spleen cell populations able to transfer experimental hypersensitivity pneumonitis (M. faeni sensitized and cultured) and those unable to transfer experimental hypersensitivity pneumonitis (ovalbumin sensitized and M. faeni cultured). Planning reduced the proportion of B cells from 53% to 11% and of Ia+ cells from 54% to 11%. Further lysis of Ia+ cells from the SIgM(+)-depleted population reduced Ia+ cells to 6%. Thy1+ cells increased from 26% to 55% after panning and to 72% after Ia+ cell lysis. Cultured M. faeni-sensitized spleen cells could transfer experimental hypersensitivity pneumonitis. Depletion of SIgM+ cells enhanced and depletion of Ia+ cells did not affect the capacity to transfer experimental hypersensitivity pneumonitis. The CD4+ cells from M. faeni-sensitized animals were 47% CD45RBhi, 36% CD44+ and 0% LECAM-1hi before culture with M. faeni and 48% CD45RBhi. They were 34% CD44+ and 27% LECAM-1hi after culture. The origin of the cells (from M. faeni- or ovalbumin-sensitized animals) did not affect the phenotype of the CD4+ cells, either before or after culture with M. faeni. We conclude that the active cells in spleen cell cultures are SIgM-, Ia-, CD4+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)