Skin test reactivity and in vitro responses to microbes and microbial antigens.

In the present study the relationships between skin reactivity, leucocyte migration inhibitory factor (LIF) production and lymphocyte transformation in healthy volunteers and newborns were investigated. LIF synthesis was assessed by the two-step agarose migration method and cellular proliferation by the incorporation of iododeoxyuridine. The following soluble antigens and whole microbes were used: purified protein derivative of tuberculin (PPD), bacille Calmette-Guérin (BCG), streptokinase-streptodornase (SK-SD), Streptococcus Beta-haemolyticus, group A, Dermatophytin O (DO) and Candida albicans. The results indicated a significant correlation between skin reactivity and in vitro tests with soluble antigens and that, of the in vitro tests used, lymphocyte transformation correlated better with skin test than LIF production. Furthermore, soluble antigens gave better correlations with skin tests than whole microbes. Experiments with cord blood cells demonstrated that they did not respond to antigens but were activated by whole microbes. Thus the whole microbes appear to contain mitogenic components.