No abstract

A diminished chemotactic response was observed with the neutrophils of a patient with the Chediak-Higashi syndrome, who was not in the accelerated phase of the disease. An abnormally low release of myeloperoxidase from these cells during phagocytosis was also noted; this resulted in a decreased iodination capacity and probably also caused the defect in the intracellular killing of bacteria by the neutrophils. The level of cyclic AMP in these cells was elevated, but decreased after treatment with ascorbate either in vitro or in vivo. During ascorbate therapy, the bactericidal activity of the neutrophils normalized, whereas the chemotactic response remained low. Nevertheless, the patient had significantly less infections during ascorbate therapy. The bleeding tendency, due to a storage-pool disorder of the Chediak-Higashi platelets, was unaffected by treatment with ascorbate. The patient's lymphocytes did not display any activity in antibody-dependent lymphocytotoxicity. This defect was not affected by treatment with ascorbate either.

Peripheral lymphocytes from individuals who had been thymectomized in adult life for myasthenia gravis (MG) or for other, nonimmunological reasons showed a moderate decrease in proliferative response capacity to several T-cell mitogens as compared to lymphocytes from normal individuals. The decrease of the response to mitogens and allogeneic lymphocytes was 20-30% within 5 years after thymectomy and about 50% more than 15 years after thymectomy. A comparable decrease in lymphocyte proliferative response capacity was found in healthy aged humans (68-97 years old). Analysis of T lymphocytes from both aged and thymectomized individuals with monoclonal (OKT) antibodies showed a similar pattern: the proportion of T lymphocytes binding OKT6, OKT10, or OKI1 were found. A biochemical parameter for human T-cell differentiation, the lactate dehydrogenase (LDH) isoenzyme pattern, showed a significantly lower H/M ratio in the group of elderly people compared to young individuals. Furthermore, among patients thymectomized for MG, a significant correlation was observed between the LDH isoenzyme pattern of the T lymphocytes and the proliferative response to mitogens of these cells. In contrast, in healthy thymectomized individuals the LDH isoenzyme pattern appeared to be normal. These findings indicate that, after thymectomy or involution of the thymus, at least part of the peripheral blood T lymphocytes have properties different from those of the cells of young individuals. These cells might represent immature and/or not fully differentiated lymphocytes.

No abstract