Elimination of mycoplasma from various cell cultures

Elimination of Mycoplasma from cell cultures by means of specific bovine antiserum

Heifers were immunized against Mycoplasma arginini, M. fermentans, M. hyorhinis and M. orale and the antisera were applied for elimination of these species from cell cultures. From fifteen out of nineteen contaminated human and animal cell cultures the mycoplasmas could be eliminated by treating the cells with medium with 10% or 20% antiserum (eight cases) or antiserum combined with one or two antibiotics (six cases). In ten cases two treatments were sufficient, in four cases respectively four, six or eight (2 X) treatments were necessary, in one case antiserum combined with a heat treatment (42 degrees C) was successful. The efficacy of the treatment depended on the antibody titer of the serum, the contaminating mycoplasm species (M. arginini being more difficult to eliminate than the other three species) and the cells involved. The bovine sera were not cytotoxic, except for a slight toxicity for a mouse lymphoma cell line. The application of specific bovine antiserum for elimination of mycoplasmas is an easy and often successful method.

Antibodies and antigen expression in human melanoma detected by the immune adherence test

By means of a modified immune adherence (IA) technique, sera from melanoma patients were tested for the presence of antimelanoma antibodies. In total 13/73 sera tested showed a positive IA reaction of which 4/6 sera showed a positive reaction in the autologous situation. Sera from 33 patients with other tumors, 7 patients with non-neoplastic diseases and 50 healthy individuals did not show any IA reactivity towards melanoma cells. The reaction seemed to be selectively directed against tumor-associated antigens (TAA) on melanoma cells. No correlation with the stage of the disease could be found. Longitudinal studies indicated that conversions in antibody activity did not correlate with the clinical state of the patients. There was also no correlation with the corresponding in vitro data obtained in cell-mediated immunity tests. Cell lines and short-term cultures originating from tumors from different melanoma patients shared a common antigenicity. The expression of TAA on cells from a melanoma cell line fluctuated significantly during prolonged culture. The expression of TAA was influenced by the culture conditions and the growth state of the cells. A relation between TAA-expression and cell cycle phase was demonstrated.

The influence of different isolation procedures and the use of target cells from melanoma cell lines and short-term cultures on the non-specific cytotoxic effects of lymphocytes from healthy donors

In parallel studies the effects of FHL1 and PNL on plated melanoma cells from cell lines and short-term cultures were compared. FHL showed more frequent and also stronger cytotoxic and/or growth-inhibiting effects than PNL. On melanoma target cells from cell lines both FHL and PNL showed more frequent and stronger cytotoxic and/or growth-inhibiting effects than on melanoma target cells from short-term cultures. In the individual donors the percentage of monocytes and EAC-rosette-forming cells in FHL was significantly higher than in PNL. A significant correlation was found between multiplication of the melanoma target cells during the period and an increased susceptibility towards lymphocytes from healthy donors. Melanoma target cells from cell lines were not more fragile, or more susceptible to unfavourable culture conditions than cells from short-term cultures, since non-lymphocytic "effector" cells showed much weaker cytotoxic and/or growth-inhibiting effects than lymphocytes from healthy donors. Cytotoxic effects of lymphocytes from healthy donors were also registered on target cells from a mammary carcinoma and an osteosarcoma cell line. No significant differences in the cytotoxic effects of lymphocytes from healthy donor were observed when tested on mycoplasma-contaminated melanoma cells and the same cells made mycoplasma-free. Mitomycin-C-treated lymphocytes retained their cytotoxic effects. Lymphocytes from a healthy donor tested on different occasions on the same melanoma cells from a short-term culture showed an incidental cytotoxic reaction.

Mycoplasmas and cell cultures

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