Abstract
When wheat germ agglutinin conjugated to fluorescein isothiocyanate is bound to hemocytes from larvae of Drosophila melanogaster, two populations of hemocytes are distinguished. One shows a fluorescent speckled surface (spk+) and the other lacks this characteristic (spk-). In mutant larvae with melanotic tumors and in larval hosts with heterospecific implants, most of the lamellocytes (a hemocyte variant involved in capsule formation and tissue rejection) are spk+, whereas the lamellocytes in nontumorous larvae are spk-. This suggests that spk+ lamellocytes are necessary for encapsulation of aberrant tissues in the mutant larvae and are responsible for rejection of foreign tissue implants.
