Correlation of in Vivo and in Vitro Assays of Immunocompetence in Cancer Patients1

Of 52 cancer patients studied for their in vitro response in lymphocyte blastogenesis assays, 50 were also studied for immunocompetence by in vivo assays. The in vivo assays used were the delayed cutaneous hypersensitivity reaction to the primary stimulus of 2,4-dinitrochlorobenzene (DNCB), and the recall reactions to four common microbial antigens. The in vitro assays were the blastogenic response to three mitogens (phytohemagglutinin, pokeweed mitogen, concanavalin A) and the mixed lymphocyte culture (MLC) reaction. The carcinoma patients demonstrated an apparent impairment of skin test reactions, but the least impairment of their lymphocyte blastogenesis reactions. The melanoma patients had notable defects in lymphocyte function tests but less impairment of the skin test reactions. Results for sarcoma patients were intermediate in both in vivo and in vitro assays. When the patients were grouped according to response to DNCB, no significant differences in responses to mitogens between the DNCB reactors and nonreactors were observed. However, the DNCB nonreactors had markedly reduced responses in MLC. Those patients with a poor response in recall antigen skin tests showed a dimin ished response in MLC and also a reduced response to the mitogens. It is postulated that antigen recognition defects can exist in cancer patients that can be detected by the DNCB or MLC tests. Additionally, there may be lympho cyte proliferation defects demonstrable in patients with certain histopathologies of cancer, especially melanoma, or in those in whom secondary immune responsiveness, as reflected by recall antigen skin tests, is impaired. These data suggest that the mitogen concanavalin A and the MLC are probably more useful screening assays of in vitro im munocompetence than is the more commonly used mitogen, phytohemagglutinin.