CANINE LEUKOCYTE HISTAMINE-RELEASE - RESPONSE TO ANTIGEN AND TO ANTI-IGE

Histamine release from canine leucocyte-enriched peripheral blood prep arations was measured in atopic, non-atopic and artificially sensitise d dogs after immunological challenge with D. farinae antigen and anti- IgE. Total cell histamine and spontaneous histamine release was also m easured. The total cell histamine content of equal leucocyte preparati ons was not statistically significant between the atopic and non-atopi c groups. At all dilutions of antigen a higher amount of histamine was released from the leucocytes of atopic dogs than was seen in the non- atopic group. No histamine release in response to D. farinae was seen in the sensitised dogs although a statistically significant increase i n serum D. farinae-specific IEE could be demonstrated after sensitisat ion (P < 0.03). Histamine release in response to anti-IgE was signific antly greater in the atopic dogs than the non-atopic dogs (P < 0.004) and the sensitised dogs (P < 0.003). There was no statistically signif icant difference in total serum IEE between the groups. The authors co nclude that the leucocytes of atopic dogs have a greater tendency to r elease histamine than those of normal and artificially sensitised dogs and that this is independent of the concentration of total serum IgE or antigen-specific IgE. They suggest that there may be immunoregulato ry abnormalities in atopic dogs intrinsic to the atopic state as is de scribed in man.