Selective modulation of B-cell activation markers CD86 and I-A(k) 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 ex posed 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 mo dulate B-cell activation markers, CD86 and I-A(k), 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 all ergens (1-chloro-2,4-dinitrobenzene, alpha-hexylcinnamaldehyde, 4-ethoxymet hylene-2-phenyl-2-oxazoline-5-one, and trinitrochlorobenzene), or irritants (benzalkonium chloride and sodium lauryl sulfate), which caused an increas e 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 dow cytome try. In mice treated with allergens an increase in the median intensity of I-A(kappa) and CD86 on B220(+) or IgG/IgM(+) B cells was observed compared to mice treated with irritants or vehicles. Mice treated with allergens dem onstrated an increase in the median intensity of CD86 on B220(+) B cells th at was dose dependent and peaked at 72 h following the find allergen treatm ent. The increase in the median intensity of I-A(kappa) also was dose depen dent but peaked at 96 h. Finally, T and B cells isolated from both allergen - and irritant-treated mice demonstrated an increase in [H-3]thymidine inco rporation compared to vehicle-treated and naive mice at 72 h following the final chemical treatment. The results suggest that B cells isolated from DL N of allergen-treated mice are activated and proliferating. Analysis of B-c ell activation markers may be useful in differentiating allergen and irrita nt responses in the draining lymph nodes of chemically treated mice. (C) 19 99 Academic Press.