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Allergic reactions due to whole body, body parts and fecal products of cockroach (CR) are characterized by inflammatory reaction that may lead to symptoms of rhinitis or asthma in atopic individuals. Although the majority of T cells at the site of CR hypersensitivity are not antigen specific, the cellular subset and cytokine receptors that participate and control the outcome of the reaction have not been fully studied. In this study, we have used fluorescent activated cell sorter (FACS) analysis to characterize the activation marker and cytokine profile of antigen specific and bystander T cells after in vitro stimulation of peripheral blood lymphocytes with whole body extract of CR antigen. There was significant enhancement of CD69 on blast and bystander T cells in all atopic subjects compared to non-atopics. Both antigen specific and bystander T cells showed increased expression of HLA-DR, CD25 and CD71 in 9 of 11 atopic patients compared to control. There was also an increase in CD45RA+ and a decrease in CD45RO+ cells following antigen stimulation. These results correlated with the increase in the early apoptotic cells observed in patients as measured by Annexin V stain. Our data revealed that there was no difference in the expression of CD95 in both stimulated and bystander T cells. However, there was enhancement of FasL by CR antigen, suggesting that the increased apoptosis that was observed was probably due to the Fas/FasL interaction. Positive intracellular IL2, IL-4 and IFN-gamma in T cells were observed in only the antigen specific blast cells in 83% of patients studied. These results suggest interplay of memory T cell response, apoptosis, and activated bystander T cells activities in maintaining cellular homeostasis during allergic reaction in cockroach sensitive atopic subjects.

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Abstract. Toxoplasma antigen and Toxoplasma immune complex were shown to induce increased production and release of acid hydrolases from macrophage cell line P388D in a concentration-dependent manner. Antigen concentrations of 10-50 g/ml gave a 2-4-fold increase in the activities of acid proteinase, acid phosphatase, and phospholipase A 2 compared with control cells without antigen. Results were similar for immune complex concentrations of 30-80 g/ml compared with controls. No significant lactate dehydrogenase activity was detected in the culture medium, indicating that enzyme release was selective and not due to cell death. These results suggest that increased release of acid hydrolases may play a role in the inflammatory lesions observed in Toxoplasma encephalitis.