Vitamin A Status and the Antibody Response to Bacterial Antigens

The antibody response of vitamin A-deficient rats was determined after immunization with bacterial antigens that differ in structure and immunological type. Primary antibody responses, measured as antigen-specific plaque-forming cells (PFC) or plasma immu-noglobulin (Ig) concentration, were significantly reduced in vitamin A-deficient rats immunized with polysaccharide antigens (pneumococcal or meningococcal types) or with protein antigens (tetanus toxoid or sheep red blood cells). In marked contrast, the antibody response to bacterial lipopolysaccharides was normal, even in animals with physical signs of deficiency. Because the response to polysaccharide and protein antigens is regulated by T lymphocytes while that to li-popolysaccharides is T cell-independent, these data suggest that impairments in T cell function may be responsible for the poor antibody responses. However, the number of T lymphocytes was unaffected, or only modestly changed. Also, antibody production per se was not impaired, a...