Selective Modulation of B-Cell Activation Markers CD86 and I-Ak on Murine Draining Lymph Node Cells Following Allergen or Irritant Treatment

It is well known that T cells are key effector cells in the development of allergic contact dermatitis. However, we and others have shown that mice exposed to contact allergens show a preferential increase in B lymphocytes in the draining lymph nodes (DLN) as seen by an increase in the percentage of B220+ or IgG/IgM+ cells. The purpose of the present investigation was to determine whether chemical allergens, in contrast to irritants, would modulate B-cell activation markers, CD86 and I-Ak, on B cells isolated from DLN of treated mice using the local lymph node assay (LLNA) protocol. Mice were treated on the ears for 3 consecutive days with concentrations of allergens (1-chloro-2,4-dinitrobenzene, α-hexylcinnamaldehyde, 4-ethoxymethylene-2-phenyl-2-oxazoline-5-one, and trinitrochlorobenzene), or irritants (benzalkonium chloride and sodium lauryl sulfate), which caused an increase in the number of DLN cells. The DLN were excised 72 h following the final chemical treatment, and the cells were prepared for analysis by flow cytometry. In mice treated with allergens an increase in the median intensity of I-AK and CD86 on B220+ or IgG/IgM+ B cells was observed compared to mice treated with irritants or vehicles. Mice treated with allergens demonstrated an increase in the median intensity of CD86 on B220+ B cells that was dose dependent and peaked at 72 h following the final allergen treatment. The increase in the median intensity of I-AK also was dose dependent but peaked at 96 h. Finally, T and B cells isolated from both allergen- and irritant-treated mice demonstrated an increase in [3H]thymidine incorporation compared to vehicle-treated and naı̈ve mice at 72 h following the final chemical treatment. The results suggest that B cells isolated from DLN of allergen-treated mice are activated and proliferating. Analysis of B-cell activation markers may be useful in differentiating allergen and irritant responses in the draining lymph nodes of chemically treated mice.