A tissue type test is a blood test that measures substances called antigens on the surface of body cells and tissues. Checking the antigens can tell if donor tissue is safe (compatible) for transplant to another person. This test may also be called HLA typing. Antigens can tell the difference between normal body tissue or foreign tissue (for example, tissue from another person's body). Tissue type helps find the best match for tissues or blood cells (such as platelets). Some times tissue type test is done to check the autoimmune diseases.