Abstract: In a separate report we demonstrated that B5 cluster antigens acts as a leading factor for ocular injuries. The question is why in some patients, these antigens does not produce the same lesions. This may be due to a genetic factor(s) which determine resistance to ocular lesions. Two HLA antigens attracted our attention as possible factors. One from the class I (CW4), and the other from the class II (DQW1). DQW1 antigen suppresses immune response to streptococcal cell wall antigens. HLA-B5 normal individuals has increased response to streptococcal antigens. Streptococcal antigens may play a role in the pathogenesis of aphthous ulcers (…KANEKQ...). DQW1 is decreased in BD patients with ocular lesions. We suggest therefore that the presence of B5 and the absence of DQW1 will increase the risk of ocular involvement while the presence of DQW1 acts as a protective factor. This phenomenon may be related to streptococcal cell wall antigens.