Sequential studies of melanoma leukocyte-dependent antibody activity in melanoma patients

Sequential assays of leukocyte dependent antibody (LDA) activity against melanoma cells were carried out on melanoma patients with localized tumour growth before and after surgical removal of their tumour. In approximately a third of the patients, LDA activity appeared in their sera after surgical removal of their tumour and this showed a gradual decline over several months. The absence of melanoma LDA in their sera prior to surgery appeared to result from the presence of serum blocking factors against LDA in their sera prior to surgical removal of the melanoma. Melanoma LDA in the pre-surgery sera, could be shown by removal of blocking factors by gel chromatography procedures and the “unblocked” LDA appeared specific for melanoma cells. In a second group of patients, no LDA activity was seen and a third group showed high levels which were present before surgery and showed no significant decline after surgical removal of their melanoma. The second group of patients were mainly males who also had a high incidence of regional lymph node involvement whereas the third group were all multiparous women. The present data do not allow evaluation of the prognostic significance of these respective patterns of LDA activity. The results indicate the melanoma LDA can be detected in a high proportion of patients at an early stage of tumour growth. They confirm our previous findings of blacking factors against melanoma LDA in patients with disseminated melanoma and establish that the LDA blocking activity has biological significance in relation to tumour growth in melanoma patients.