2 DISTINCT NON-T HELPER TYPE-2 INTERLEUKIN-4(-CELL CYTOKINE ANALYSIS() CELL SUBSETS IN MICE AS REVEALED BY SINGLE)

We have previously defined four murine CD4(+) peripheral T cell subset s, fractions (Fr.) I - IV, based on expression of the 6C10 and 3G11 de terminants (Hayakawa, K. and Hardy, R. R., J. Exp. Med. 1988. 168: 182 5). These subsets also show distinctive levels of other cell surface m arkers: the two minor subsets, Fr. III and Fr. IV, are both CD45RB(low /-), L-selectin (Mel-14)(-) and CD44(hi), characteristic of secondary T cells. The patterns and levels of cytokine production by individual cells in each subset were determined by bioassay for interleukin (IL)- 2/IL-4 or IL-4/interferon (IFN)-gamma production after anti-CD3 stimul ation. Our data revealed that these four phenotypically defined subset s largely coincide with clusters of cells showing uniform distinctive cytokine profiles, i.e. IL-2(+)/IFN-gamma(-)/IL-4(-) (Fr. I and Fr. II , L-selectin(+)), IL-2(+)/IFN-gamma(+)/IL-4(+) (Fr. III, L-selectin(-) ), and IL-2(-)/IFN-gamma(low/-)/IL-4(+) (Fr.IV, L-selectin(-)). Beside s these subsets, an L-selectin-negative cell subfraction within Fr. II appears to represent a transitional population between the IL-2(+)/IF N-gamma(-)/IL-4(-) stage and the IL-2(+)/IFN-gamma(+)/IL-4(+) stage. T aken together, these results demonstrate the presence of two IL-4(+) s econdary T cell subsets with distinct cytokine production patterns, an d show that the majority of IL-4(+) cells found in healthy adult labor atory mice co-produce IFN-gamma, and thus are not typical T helper typ e 2 cells.