ADOPTIVE TRANSFER OF EXPERIMENTAL HYPERSENSITIVITY PNEUMONITIS - CD4+CELLS ARE MEMORY AND NAIVE CELLS

We previously demonstrated that CD4+ cells are responsible for transfe r of adoptive murine experimental hypersensitivity pneumonitis. To fur ther characterize the CD4+ cells as naive or memory cells, we depleted Micropolyspora faeni-sensitized cultured C3H/HeJ spleen cells of surf ace IgM+ cells by panning and Ia+ cells by lysis. We measured the prop ortion of CD4+ cells that expressed CD45RB, CD44 or LECAM-1 (markers u sed to distinguish memory from naive CD4+ cells) in spleen cell popula tions able to transfer experimental hypersensitivity pneumonitis (M. f aeni sensitized and cultured) and those unable to transfer experimenta l hypersensitivity pneumonitis (ovalbumin sensitized and M. faeni cult ured). 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 f rom 26% to 55% after panning and to 72% after Ia+ cell lysis. Cultured M. faeni-sensitized spleen cells could transfer experimental hypersen sitivity pneumonitis. Depletion of SIgM+ cells enhanced and depletion of Ia+ cells did not affect the capacity to transfer experimental hype rsensitivity pneumonitis. The CD4+ cells from M. faeni-sensitized anim als were 47% CD45RB(hi), 36% CD44+, and 0% LECAM-1(hi) before culture with M. faeni and 48% CD45RB(hi). They were 34% CD44+ and 27% LECAM-1( hi) after culture. The origin of the cells (from M. faeni- or ovalbumi n-sensitized animals) did not affect the phenotype of the CD4+ cells, either before or after culture with M. faeni. We conclude that the act ive cells in spleen cell cultures are SIgM- Ia-, CD4+ T cells. The CD4 + cells are phenotypically a mixture of memory and naive cells. There are differences in the ability of cultured cells to adoptively transfe r experimental hypersensitivity pneumonitis, which are dependent on th e nature of the donor but not on the phenotype of the cell population.