IL-5 EXPRESSED BY CD4(-INFECTED PATIENTS() LYMPHOCYTES FROM ECHINOCOCCUS MULTILOCULARIS)

IL-5 is a major factor inducing differentiation of B lymphocytes into immunoglobulin-producing cells as well as a main regulator of eosinoph ils. Recently, we have shown that peripheral blood mononuclear cells ( PBMC) from patients with alveolar echinococcosis (AE) express IL-5 mRN A after stimulation with crude Echinococcus multilocularis (E.m.) anti gen. To characterize the observed response in lymphocyte subpopulation s, we cultured patients' PBMC in the presence of E.m. crude antigen fo r 18 h. PBMC were separated from seven patients by fluorescence-activa ted cell sorting (EPICSorter) into CD4(+) and CD8(+) subpopulations an d from an additional seven patients by magnetic cell sorting (MACS) in to CD4(+), CD8(+) and the CD4(+)/CD8(+) depleted fractions. mRNA was d etected by reverse transcriptase-polymerase chain reaction (RT-PCR) fo r the cytokines IFN-gamma, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, as wel l as for beta-actin as control. IL-4 and IFN-gamma expression was posi tive in all of the patients in the stimulated CD4(+) subgroup. IL-5 mR NA expression was detected in eight out of 14 CD4(+) samples (58%) and not observed in the other subpopulations, or the unstimulated and hea lthy controls. Co-expression of other Th2 cytokines in the eight patie nts expressing IL-5 mRNA was found in five patients for IL-3 and in se ven for IL-10. Expression of IL-5 and both Th2 cytokines (IL-3 and IL- 10) was only observed in patients judged as critically ill. Out of the six patients who were regarded as cured after radical operation or as stabilized with or without chemotherapy, only two expressed IL-5. Out of those eight patients considered as critically ill, six expressed I L-5 mRNA and five of these co-expressed IL-3 and IL-10. Thus, we concl ude that specific antigenic challenge of PBMC from patients with activ e or previous AE induces an IL-5 response of CD4(+) lymphocytes. The e xpression of Th2-type interleukin mRNA is significantly more frequent in patients clinically judged as progressive. Furthermore, IgE was ele vated only in patients regarded as critically ill (six out of eight). In none of the patients were eosinophils elevated. These data support a Th2-type immune response in patients with chronic E. multilocularis infection.