background: perforin is known to be important in cytolytic activity mediated by natural killer (nk) cells.   objective: to study the relationship between the efficiency of nk and lymphokine-activated killer (lak) cells activity, and the expression of perforin and hla class i molecules.   methods: lak cells were generated by in vitro culturing of human peripheral blood lymphocytes (pbls) in the ...

Some years ago Koutras presented a method of constructing a conformal Killing tensor from a pair of orthogonal conformal Killing vectors. When the vector associated with the conformal Killing tensor is a gradient, a Killing tensor (in general irreducible) can then be constructed. In this paper it is shown that the severe restriction of orthogonality is unnecessary and thus it is possible that m...