The presence of blocking factors in Brugia malayi microfilaraemic patients.

Serum from microfilaraemic patients have been shown to be unable to promote the antibody-dependent, cell-mediated adherence reaction to infective larvae of Brugia malayi in vitro. In this study, it was found that peripheral leucocytes from microfilaraemic patients were also incapable of promoting the adherence reaction even when incubated with serum of tropical pulmonary eosinophilia (TPE) patients. The TPE sera would normally promote the most intense adherence reaction. It was further shown that preincubation of normal human peripheral leucocytes with sera of microfilaraemic patients would similarly render them incapable of adherence. Such preliminary studies suggest that blocking factors may be present in microfilaraemic patients.