Sequential changes in peripheral blood leukocyte adherence inhibition (LAI) reactivity during progressive growth and...

Sequential changes in canine transmissible venereal sarcoma (CTVS) extract-induced leukocyte adherence inhibition (LAI) reactivity of peripheral blood leukocytes (PBL) were monitored in dogs from the time of tumor inoculation through progressive growth and spontaneous regression or surgical excision of CTVS. The time-course profiles of LAI reactivity of tumor dog PBL correlated with the clinical stage of tumor growth, substantiating our previous findings in a cross-sectional study. The kinetics of the time-course appearance of LAI reactivity observed and the demonstration of a rapid anamnestic response following tumor challenge indicate further that LAI is a reliable in vitro measure of in vivo tumor immunity. A significant increase in CTVS antigen extract-induced LAI reactivity observed in the PBL during tumor regression suggest that LAI reflects a function effector cell mechanism associated with spontaneous regression of CTVS. By contrast, absence of significant LAI reactivity of PBL during progressive tumor growth suggests the presence of serum blocking factors. In addition a substantial rebound in LAI reactivity observed in the PBL of dogs 3 to 7 days following surgical excision of progressively growing CTVS provides further evidence that tumor-cell components are associated with progressive tumor growth and diminished LAI reactivity.