Accessory cell populations in draining lymph nodes of lambs in the elicitation phase of DNCB-induced contact hypersensitivity

The effect of experimentally induced contact hypersensitivity on accessory cell populations in draining lymph nodes of lambs was studied. Previous stu dies of draining lymph nodes of lambs during the elicitation phase of CHS h ave shown that there are significant changes in T-cell subpopulations, part icularly CD4(+) cells and gamma delta T-cells, but the behaviour of accesso ry (antigen presenting) cell populations was not investigated. The immunohi stochemical presence of accessory cell populations was determined using mar kers for CD68, Pan MHCII, MHCII DQ, MHCII DR, OvCD1w1 (putative human CD1a/ c-like) and OvCD1w2 (human CD1b-like). Ten lambs were sensitised, and 14 da ys later re-challenged, by applying the hapten di-nitro-chloro-benzene (DNC B) together with an acetone and olive oil (AOO) vehicle, onto the skin. Cry osections of the draining lymph nodes were stained immunohistochemically fo r the accessory cell markers. Using an image analysis system, the areas of staining in the lymph nodes from the challenged animals were compared with measurements in control animals. A significant increase in staining for CD6 8(+) cells was detected in the cortex of the DNCB-treated group (g=0.003). A significant increase in staining for the Pan MHCII marker was also observ ed in the DNCB group (p=0.013). These results show that MHCII+ cells and CD 68(+) cells constitute a prominent cell population in the cortex of the reg ional lymph nodes of lambs in the late elicitation phase of DNCB-induced co ntact hypersensitivity. (C) 2000 Elsevier Science B.V. All rights reserved.