Specific and nonspecific cell-mediated effector mechanisms have been simultaneously assayed in 15 aged humans. 8 were female and 7 male, including a 114-year-old male in remarkably good health. Proliferative response to alloantigens, the generation of T killer cells and the ability to express cell-mediated lympholysis as well as the presence of natural cell-mediated cytotoxicity against K562 tumor cell line and the capacity to mount an ADCC response to RhD+ human red blood cell sensitized with anti-D antisera, revealed that in the human aged, while T function significantly declines, nonspecific cell-mediated effector mechanisms are operative.

Generation of effector cells, the expression of cell mediated lympholysis (CML) and the reactivity of mononuclear cells in solid cultures, were explored in patients with Systemic Lupus Erythematosus (SLE). While proliferative responses to alloantigens were comparable to the controls, a significant decrease in CML capacity was found in SLE T lymphocytes; further, T cells stimulated with a T cell mitogen in solid cultures showed a diminished proliferative response to soluble factors. Functional cell interaction defects rather than intrinsic T cell abnormalities may be operating in SLE.

A and -B antigens incidence were investigated in 100 cases of Seronegative Spondyloarthropathics and in 303 control individuals of a Venezuelan Mestizo population. Significative increased incidence of B27 was found among 69% of patients with ankylosing spondylitis and 68% with Reiter syndrome being the incidence in the control group o f 2.9%. The B27 negative patients showed 40.4% positivity for Bw35, with spondylitic lcsion in 12 out of 17 cases. Our results question the applicability of B27 as diagnostic criteria in the Mestizo patients bearers of a Seronegative Spondyloarthropathy and suggest the need to investigate further the role of antigens of the B locus in the pathophysiology of these clinical cntitics.

Anti-Leu-4 is a murine monoclonal antibody that defines a molecule of 20,000 to 25,000 daltons present on all mature T lymphocytes in man. When cultured in the presence of 10 to 1000 ng/ml anti-Leu-4, the T cells of most individuals proliferate with peak responses on the third day of culture. T cells of both helper and suppressor lineages proliferate, but only in the presence of monocytes. Approximately 40% of individuals tested responded weakly or not at all to anti-Leu-4, despite normal responses to other stimuli. The variation in responsiveness between individuals could not be explained by differences in Leu-4 antigen density on the surface of T cells, differences in the rate of Leu-4 antigen modulation, or structural differences in the Leu-4 molecule as defined by the method of two-dimensional polyacrylamide gel electrophoresis. In the presence of monocytes from high responders, the T cells from low responders proliferated vigorously to anti-Leu-4, whereas monocytes from low responders failed to support proliferation by high responder T cells. On the other hand, low responder monocytes did not prevent T cells from proliferating in the presence of high responder monocytes. These results suggest that the failure of some individuals to respond to anti-Leu-4 is due to the absence or dysfunction of an essential monocyte population.