HLA and Disease Susceptibility in Tamil Nadu, S. India.

Result on HLA polymorphism in the populations of Tamil Nadu, South India are analysed for HLA association with various diseases like pulmonary tuberculosis, leprosy, psoriasis, rheumatoid arthritis, iridocyclitis and Eale's disearse. These studies revealed: i) association of psoriasis with HLA B17 and DR7 is highly significant in Vellala related group and this is attributed to founder effect-hitch hiking of a disease producing gene linked to these alleles, as the population migrated, ii) different castes differ from one another in their HLA allelic and haplotype polymorphism, iii) HLA DR2 predispose for more severe from of pulmonary tuberculosis which transcends ethnic barrier, the susceptibility presumably being due to a generalized MHC dependent immunogenetic and pathological mechanism, iv) HLA B27 and DR4 are associated with iridocyclitis, rheumatoid arthritis and low back pain; the susceptibility may be a HLA dependent molecular mimicry process, v) HLA alleles DR2 and DR4 predispose for severe forms of the respective diseases, though not for initial susceptibility.

Frequency of HLA antibodies in south India.

Sera from 4088 pregnant women (649 antenatal bleeding and 3439 post-partum bleeding) living in Madurai, were collected and screened for anti-HLA. Α, Β and DR antibodies. 696 of them were screened for anti-HLA DR antibodies. Ten per cent (65/649) of antenatal sera and 13·4% of post-partum sera (463/3439) were positive for HLA A and Β antibodies: nonetheless the percentage of monospecific sera were almost the same in both. Screening for HLA DR antibodies were carried out using platelet absorption in test tray technique: seventy three of 696 (10·5%) were positive. The incidence of anti-HLA A, B antibodies correlates to the allelic frequencies in the population. Thus in India, collection and screening post-partum haemorrhage is the simplest and cost effective method of acquiring polyclonal sera for routine laboratory and diagnostic use.