Counteraction of the blocking of cell‐mediated tumor immunity by inoculation of unblocking sera and splenectomy: immunotherapeutic effects on primary polyoma tumors in rats

Regression of polyoma tumor metastasis by combined unblocking and bcg treatment‐correlation with induced alterations in tumor immunity status

“…In agreement with previous findings in rats carrying primary polyoma tumors (Bansal and Sjogren, 1972), antibodies cytotoxic to polyoma tumor cells with rat complement did not appear in the control animals. Such antibodies were demonstrated in all rats of the two treatment groups (group 1 of Exp.…”

“…A similar correlation between inhibited tumor growth and disappearance of blocking and appearance of antibodies specifically cytotoxic with rat complement was recently established in rats carrying primary polyoma tumors and subjected to splenectomy and unblocking serum inoculations as sole treatment (Bansal and Sjogren, 1972).…”

Alteration of in vitro anti‐tumor activity of tumor‐bearer sera by absorption with Staphylococcus aureus, cowan I

“…It has further been shown that the blocking component of serum has the gel filtration characteristics of a 7 s immunoglobulin (Hellstrom and Hellstrom, 1969;Ankerst, 1971) and that low PH eluates of fresh tumor tissue contain blocking activity (Bansal et al, 1972;Sjogren et al, 1972) and immunoglobulins of the IgG class (Ran and Witz, 1970;Sobczak and de Vaux Saint Cyr, 1971). Evidence has accumulated indicating that most of the serum blocking activity is associated with antigen-antibody complexes rather than with free antibody (Sjogren et al, 1971).…”

“…The technique used has been previously described (Bansal et a/., 1972). Protein-A-treated and untreated sera to be tested for blocking activity were added in 0.1 ml vol to the wells of a Microtest I I plate (No.…”

Multimodal immunotherapy of primary gastrointestinal tumors in rats. 1 Histologic correlation

“…For technical reasons, plasmapheresis and extracorporeal immunoabsorption procedures can optimally be performed in larger animals or man.7,8 Therefore, unblocking serotherapy was used in this experiment to counteract serum blocking activity in viuo along with splenectomy which has been shown to decrease temporarily serum blocking activity in tumor host. 13 It is recognized that effects obtained by unblocking serotherapy might be due to mechanisms other than its unblocking effect, such as complement dependent cytotoxic activity13 or arming effect.s…”