Soluble HLA (sHLA) are potential tumour markers released in order to counter immune surveillance. sHLA-class II is less known especially in acute lymphoblastic leukaemia (ALL). This study aimed to investigate soluble, surface and allelic expression of HLA Class II (sHLA-DR) in B-cell ALL patients and compare with soluble expression in normal individuals. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to measure soluble HLA-DRB1 in plasma. Flow cytometric analysis was performed to determine median fluorescence intensity in HLA-DR surface expression. HLA-DNA typing by polymerase chain reaction, sequence specific oligonucleotides, PCRSSO was performed to determine HLA-DRB1 type in ALL samples. Results showed sHLA-DRB1 (mean+SEM) was significantly increased (p=0.001) in plasma of ALL patients (0.260±0.057 μg/mL; n=30) compared to healthy controls (0.051±0.007μg/mL; n=31) of Malay ethnicity. However, these levels did not correlate with percentage or median fluorescence intensity of HLA-DR expressed on leukemia blasts (CD19+CD34+/-CD45loHLA-DR+) or in the normal B cell population (CD19+CD34- CD45hiHLA-DR+) of patients. No significant difference was observed in gender (male/female) or age (paediatric/adult). Only a trend in reduced sHLA was observed in patients carrying HLA-DR04. These results have to be validated with a larger number of samples.

Introduction: Sex shapes immune response with possible consequence on tumor immune escape. Acute lymphoblastic leukemia (ALL) predominates in males while ovarian cancer (OC) occurs in females. NK cells essential for tumor killing may have male preponderance. Association of sex, NK cell activity and malignancies is unclear. We hypothesize that sex differentially affects KIR expressions in sex-biased cancers. Method: Expression of inhibitory (KIR2DL1-5 and KIR3DL1-3) and activating (KIR2DS1-2 and 4-5 and KIR3DS1) genes in B-, T-cell ALL, OC and normal controls were determined by reverse-transcription polymerase-chain-reaction. Result: All normal males (but not females) expressed the framework genes and generally maintained haplotype A, except KIR3DL1. Normal females expressed more activating KIRs. Frequencies of KIR2DL1, 2DL4 and 2DS2 were significantly reduced among ovarian cancer patients. Sex difference in frequencies of KIR expression was not detected in ALL as majority were undetectable except framework gene KIR3DL2, was more frequent among T-ALL. Conclusion: Cancers may be associated with reduced KIR expression and influence of sex requires investigation.