Abstract: Natural killer (NK) cells possess the inherent capacity to kill various tumor and virally infected cells. A large family of NK cell receptors belongs to the C-type lectin super-family. Genes in the NK gene complex encode type II receptors and examples include the families of NKR-P1, Ly-49, and NKG2 receptors. Examples of other C-type lectin-like receptors that occur as individual genes are CD94, CD69 and AICL. The invention includes a cDNA that encodes a predicted protein of 191 amino acid residues having similarity to the carbohydrate recognition domain of C-type lectins. The predicted protein of LLT1 shows 59 and 56% similarity to AICL and CD69, respectively. A monoclonal antibody (L9.7) against LLT1 receptor was generated. Binding of mAb L9.7 to surface LLT1 induced interferon gamma production in YT, a human NK cell line, as well as in resting and IL-2 activated NK cells, without modulating cytotoxicity.

Abstract: Natural killer (NK) cells possess the inherent capacity to kill various tumor and virally infected cells and mediate the rejection of bone-marrow grafts in lethally irradiated animals. A large family of NK cell receptors belong to the C-type lectin super-family. Genes in the NK gene complex encode type II receptors and examples include the families of NKR-P1, Ly-49, and NKG2 receptors. Examples of other C-type lectin-like NK cell receptors that occur as individual genes are CD94, CD69, and AICL. The invention includes a cDNA that encodes a predicted protein of 191 amino acid residues having similarity to the carbohydrate recognition domain of C-type lectins. The predicted protein of LLT1 shows 59 and 56% similarity to AICL and CD69, respectively. The predicted protein does not contain any intracellular ITIM motifs indicating the LLT1 protein may be involved in mediating activation signals.

Abstract: Natural killer (NK) cells constitute the third major population of lymphocytes. They possess the inherent capacity to kill various tumor and virally infected cells and mediate the rejection of bone marrow grafts. A large family of NK cell receptors belong to the C-type lectin family and are localized to NK gene complex on chromosome 6 or 12 in the mouse or human, respectively. Genes in the NK gene complex are all type II receptors and examples include the families of NKR-P1, Ly-49, and NKG2 receptors. Examples of other C-type lectin-like NK cell receptors that occur as individual genes are CD94, CD69, and AICL. Here we report the molecular characterization of a human lectin-like transcript (LLT1) expressed on NK, T, and B cells and localized to the NK gene complex within 100 kb of CD69.