Soluble HLA in Human Body Fluids Donnie Aultman, Irena Adamashvili, Kamalakar Yaturu, Marlyn Langford, Frank Gelder, Michael Gautreaux, G. E. Ghali, and John McDonald ABSTRACT: There is a growing body of information about the soluble forms of HLA in serum but there are only a few reports discussing sHLA in other body fluids. We quantitated sHLA-I and sHLA-II concentrations in sweat, saliva and tear samples from five normal individ- uals with known HLA-phenotypes. We also studied sweat samples from an additional 12 normal nonphenotyped subjects, as well as in CSF of 20 subjects with different illnesses, using solid phase enzyme linked immunoassay. Sweat, saliva and tears from normal subjects were found to contain very low or nondetectable amounts of sHLA-I. In contrast, sHLA-II molecules were found in each of these body fluids, although, with considerable variation be- tween individuals. The presence of sHLA-II in saliva was further confirmed by Western-blotting. It was observed that sHLA-II having molecular mass of 43,900 and 18,100 daltons was comparable with that found in serum from normal individuals. In addition, no association of sHLA-II levels with allospecificities in either body fluid or in serum was apparent. The results of CSF sHLA concentrations in different diseases were as follows: (1) High CSF SHLA-I levels were measured during viral encephylitis (n = 3), while none of these patients con- tained sHLA-II in CSF; (2) The levels of sHLA-II, but not sHLA-I were elevated in CSF of patients during seizure (n = 6) and of patients with neonatal hepatitis (1 of 2) or with connective tissue disease accompanied with viral infection (n = 2); (3) No CSF sHLA-I or sHLA-II could be detected at polyneuropathy (n = 2), or in patients with syphilis (n = 3), or leukemia (n = 2) with evidence of neurologic involvement of central nervous system. Taken together, it may be concluded that the presence of sHLA in several body fluids is physiologically normal. It appears that sHLA-II is the predominant class of HLA molecules present in different body fluids. We propose that the system responsible for sHLA-II production in various body fluids must involve different mechanisms than those responsible for sHLA-I synthesis in serum. Human Im- munology 60, 239 –244 (1999). © American Society for Histocompatibility and Immunogenetics, 1999. Pub- lished by Elsevier Science Inc. KEYWORDS: soluble HLA Class I; soluble HLA Class II; major histocompatibility complex; ELISA ABBREVIATIONS sHLA soluble human leucocyte antigens sHLA-I soluble human leucocyte Class I antigens sHLA-II soluble human leucocyte Class II antigens CSF cerebral spinal fluid Mab monoclonal antibody m.w. molecular weight INTRODUCTION Soluble HLA-I (sHLA-I) and soluble HLA-II (sHLA-II) are known to be normal constituents of serum [1– 4]. SHLA-I is present in the urine of people with chronic renal disease [5] and in peritoneal dialysate from patients with chronic renal failure [6] as well as in sweat, al- though in very small quantities [7]. SHLA-I was also detected in the cerebrospinal fluid (CSF) of patients with varicella meningitis [8]. It was also present in CSF in AIDS patients and its concentration correlated with the stage of the disease [9]. SHLA-II is present in the urine of normal subjects and the peritoneal dialysate in patients with chronic renal failure [10]. It has also been reported in synovial fluid with active rheumatoid arthritis [11]. The relationship between sHLA-I and II has not been extensively studied. We found no correlation between sHLA-I and II in the serum of normal subjects or in transplant patients with rejection or infection [10]. Stud- From the Louisiana State University Medical Center, Shreveport, LA 71130, USA. Address reprint requests to: John C. McDonald, M.D., Professor and Chairman, Department of Surgery, Louisiana State University Medical Center, P.O. Box 33932, Shreveport, LA 71130, USA. Tel: 318-675- 6100; Fax: 318-675-6141. Received September 11, 1998; revised December 3, 1998; accepted De- cember 4, 1998. Human Immunology 60, 239 –244 (1999) 0198-8859/99/$–see front matter © American Society for Histocompatibility and Immunogenetics, 1999 Published by Elsevier Science Inc. PII S0198-8859(98)00122-0