Production of lymphoid tumours in hamsters by direct implantation of normal human leukocytes

Establishment and characterization of two hamster macrophage cell lines

Two hamster macrophage cell lines (HM-1 and HM-2) were established in vitro from lymphoid tumors produced in hamsters by direct implantation of normal human umbilical cord leukocytes. Despite long-term culture, both cell lines maintained the morphological, functional and surface characteristics of normal macrophages. It is considered that these cell lines were derived from host macrophages infiltrating the heterotransplants.

Production of lymphoid tumors in hamsters by direct implantation of normal human peripheral and umbilical cord leukocytes

Peripheral leukocytes from Epstein-Barr virus (EBV)-seropositive or seronegative normal adults, or human umbilical cord leukocytes infected or not infected with EBV, were directly transplanted into 50 newborn hamsters treated with anti-lymphocyte serum. Lymphoid tumors were produced after a latent period of 10-25 days in 39 animals: 8 of 14 recipients of seropositive donor leukocytes, 2 of 2 recipients of seronegative donor leukocytes, 13 of 15 recipients of EBV-infected cord leukocytes, and 16 of 19 recipients of non-infected cord leukocytes. EBV-determined nuclear antigen-positive human lymphoblastoid cell lines were established in vitro from tumors produced with seropositive donor leukocytes or EBV-infected cord leukocytes but not from tumors produced with seronegative donor leukocytes or non-infected cord leukocytes. The results indicate that EBV is not a prerequisite for in vivo production of tumors but necessary for in vitro establishment of lymphoblastoid cell lines from such tumors.

Surface markers on human B and T lymphocytes. VIII. Association between complement and Epstein-Barr virus receptors on human lymphoid cells

An association has been found between the Epstein-Barr virus (EBV) and complement (C3d) receptors on human lymphoid cells. The evidence was four-fold: there was a correlation between the expression of these two receptors; inhibition experiments showed that the binding sites probably are close to each other in the cell membrane, although not identical; EBV and complement receptors have been found to co-cap in either order; and lymphoid cell lines lacking complement receptors could not be superinfected with EBV.