Is it often seen, that La antibodies are positive, but Ro abs are negative?

Is it often seen, that La antibodies are positive, but Ro abs are negative?

Anti-SS-B/La antibodies are found almost always in combination with anti-SS-A/Ro antibodies and in 10 to 20 % of cases the anti-SS-A/Ro antibodies are found solely. (1) Neonatal lupus erythematosus (NLE) rarely occurs in the absence of Ro antibody; only four cases of La antibody positivity in the absence of Ro antibody have been reported. However, three of the four mothers were positive for both anti-Ro and anti-La antibodies. It is extremely rare to find La antibody in the absence of Ro antibody in both mother and infant. One case is described in the article of Neidenbach et al. (2) The significance of the finding of solely La antibody positivity is unknown, but it does support observations by Provost et al. that La antibody is significant in the pathogenesis of NLE. (2) Franceschini et al. describe an infant with cutaneous lupus lesions who, along with his mother, was positive for antibodies to La and negative for anti-Ro and anti-U1 RNP antibodies. (3) In 1989 Buyon et al. found, that antibodies to the 48-kD La antigen and its 43-kD degradation product were both found in the highest prevalence and were the antibody species most strongly associated with NLE. The individuals without detectable antibodies either to 52- or 60-kD Ro antigens each had very high levels of antibodies that reacted with the La polypeptides.

 

References:
(1) Humbel RL (1998) Autoantikörper und Autoimmunerkrankungen, Elsevier, Amsterdam

(2) Neidenbach PJ, Sahn, EE (1993) La (SS-B)-positive neonatal lupus erythematosus: Report of a case with unusual features. J Am Acad Dermatol 29, 848-852

(3) Franceschini F, Bertoli MT, Martinelli M et al. (1990) The neonatal lupus erythematosus associated with isolated La(SSB) antibodies. J Rheumatol 17, 415-417

(4) Buyon et al. (1989) Acquired Congenital Heart Block. J Clin Invest 84, 627-634 

References:
(1) Humbel RL (1998) Autoantikörper und Autoimmunerkrankungen, Elsevier, Amsterdam

(2) Neidenbach PJ, Sahn, EE (1993) La (SS-B)-positive neonatal lupus erythematosus: Report of a case with unusual features. J Am Acad Dermatol 29, 848-852

(3) Franceschini F, Bertoli MT, Martinelli M et al. (1990) The neonatal lupus erythematosus associated with isolated La(SSB) antibodies. J Rheumatol 17, 415-417

(4) Buyon et al. (1989) Acquired Congenital Heart Block. J Clin Invest 84, 627-634

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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.