Immunogenic cells in the regional lymph nodes after painting with the contact sensitizers picryl chloride and oxazolone: evidence for the presence of IgM antibody on their surface.

The lymph node cells of mice painted with contact sensitizing agents immunize recipient mice when injected into their footpads. In practice 2 × 10 nylon wool purified T cells are used from mice painted with picryl chloride or oxazolone (4-ethoxymethylene-2-phenyloxazolone). The ability of cells taken 4 days after painting to immunize other mice was abolished by treatment with rabbit complement but cells taken at 1 day were unaffected. This effect of rabbit complement was due to IgM anti-hapten antibody on the surface of antigen-presenting cells. The antibody could be eluted from the cells with appropriate picryl or oxazolone-ε-aminocaproic acid. It adhered to insolubilized anti-IgM and behaved like IgM on gel filtration. To confirm the role of this antibody, mice were rendered unresponsive with picrylated pneumococcal polysaccharide type III before being painted. This abolishes antibody production but leaves contact sensitivity intact. The lymph node cells of animals treated in this way were unaffected by rabbit complement and this suggested that antibody was required for this phenomenon. Moreover although lymph nodes normally lose the ability to immunize at day 6 after painting, the lymph node cells of unresponsive mice, which fail to make antibody immunize other mice up to day 8 after painting. This effect of unresponsiveness is reversed by the injection of serum taken 8 days after painting. It was concluded that IgM antibody which appears on the surface of lymph nodes 4 days after painting depresses their ability to immunize other mice.