Dialyzable transfer factor, obtained from frozen-thawed peripheral blood leukocytes from a single donor, was given to five anergic patients with chronic mucocutaneous candidiasis. Studies of immunological responses including delayed cutaneous hypersensitivity, in vitro antigen-induced thymidine incorporation, and production of macrophage migration inhibition factor (MIF) were conducted both before and after injection of transfer factor. Before transfer factor, none of the patients had delayed skin responses to any of the natural antigens studied. Their lymphocytes did not produce MIF after exposure to antigens in vitro and only one patient showed increased thymidine incorporation when his lymphocytes were cultured with candida and streptokinase-streptodornase (SK-SD). After injection of transfer factor, four patients developed delayed skin responses to antigens to which the donor was sensitive; no recipient reacted to an antigen to which the donor was nonreactive. Lymphocytes from recipients produced MIF when cultured with antigens that evoked positive delayed skin tests. Only one patient developed antigen-induced lymphocyte transformation and this response occurred only intermittently. Attempts to sensitize three of the patients with the contact allergen, chlorodinitrobenzene, both before and after transfer factor, were unsuccessful. The fifth patient, a 9-yr old boy with an immunologic profile similar to the Nezelof syndrome, did not become skin test-reactive or develop positive responses to the in vitro tests. These findings suggest that transfer factor acts on the immunocompetent cells that respond to antigens with lymphokine production, but has little, if any, effect on cells that respond to antigens by blastogenesis. The failure to sensitize the subjects with chlorodinitrobenzene illustrates the specificity of the immunologic effects of transfer factor, and implies that it does not function through nonspecific, adjuvant-like mechanisms. Failure of transfer factor to produce positive skin tests or MIF production in a patient with Nezelof's syndrome may be evidence that lymphokine-producing cells are thymus derived.
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