Immunology of the Mycoses

Abstract

Summary The transformation of lymphocytes in vitro in the clinical types of histoplasmosis was studied by stimulation of peripheral blood lymphocytes with histoplasmin. Lymphocytes were obtained from five healthy histoplasmin-positive and five histoplasmin-negative donors as well as five patients who had acute histoplasmosis and five patients who had chronic histoplasmosis. The measurement of incorporation of radioactive thymidine into DNA was a more sensitive indicator of lymphocyte transformation than morphology. The uptake of thymidine, as expressed by a ratio of the radioactive counts from the antigne stimulated tubes and the unstimulated tubes (E′C), was greater for the healthy histoplasmin-positive donors (median E/C 66.7) than for the histoplasmin-negative donors (median E/C 4.9). Acute histoplasmosis patients (median E/C 51.1), as a group, reacted similarly to the healthy histoplasmin-positive donors. The chronic histoplasmosis patients (median E/C 22.6), on the other hand, reacted more like the histoplasmin-negative donors. The lymphocyte transformation, appeared to be depressed according to the severity of the clinical illness as well as by the presence of serum antibodies. Also, the transformation was depressed by heating serum at 56°C in a water bath for 30 min. No antibody against histoplasmin could be demonstrated in the culture fluid by means of the C-F test even when there was strong lymphocyte transformation.