First, to validate contact-dependent tumor killing, T cells isolated from peripheral blood of human volunteers after stimulation with anti-CD3/CD28, were subjected to four experimental sets comprising of (a) T cells cultured in media alone (control), (b) T cells cultured in untreated tumor supernatant (un-primed), (c) T cells cultured in placebo-treated tumor supernatant (placebo-primed) and (d) T cells cultured in calcarea carbonica-treated tumor supernatants (calcarea carbonica-primed) for 3 days. This evidence concerns the gene CD28 and neoplasm.