A new monoclonal antibody detects a developmentally regulated mouse ecto-ADP-ribosyltransferase on T cells: Subset distribution, inbred strain variation, and modulation upon T cell activation

ADP-ribosylation of membrane proteins on mouse T cells by ecto-ADP-ribosylt ransferase(s) (ARTs) can down-regulate proliferation and function, The lack of mAbs against mouse;ARTs has heretofore prevented analysis of ART expres sion on T cell subsets. Using gene gun technology, we immunized a Wistar ra t with an Art2b expression vector and produced a novel mAb, Nika102, specif ic for ART2.2, the Art2b gene product, We show that ART2.2 is expressed as a GPI-anchored protein on the surface of mature T cells. Inbred strain-depe ndent differences in ART2.2 expression levels were observed. C57BL/6J and C 57BLKS/J express the Ag at high level, with up to 70% of CD4(+) and up to 9 5% of CD8(+) peripheral T cells expressing ART2,2, CBA/J and DBA/2J represe nt strains with lowest expression levels., T cell-deficient mice and NZW/La cJ mice with a defective structural gene for this enzyme were ART2.2 negati ve, In the thymus, ART2.2 expression is restricted to subpopulations of mat ure cells. During postnatal ontogeny, increasing percentages of T cells exp ress ART2,2, reaching a peak at 6-8 wk of age, Interestingly, ART2,2 and CD 25 are reciprocally expressed: activation-induced up-regulation of CD25 is accompanied by loss of ART2,2 from the cell surface. Nika102 thus defines a new differentiation/activation marker of thymic and postthymic T cells in the mouse and should be useful for further elucidating the function of the ART2,2 cell surface enzyme.